Methods for selectively inhibiting Janus tyrosine kinase 3 (Jak3)

ABSTRACT

Methods are disclosed for inhibiting or disrupting Janus tyrosine kinase 3 (Jak3) dependent function in cells of lymphoid or myeloid origin, especially for blocking proliferation and function of lymphocytes (e.g., T-cells, B-cells). A Mannich base compound, or a derivative or modified compound, is employed which is capable of selectively inhibiting Jak3 while affecting other protein tyrosine kinase activities to a lesser extent or not at all, to provide beneficial effects such as mitigation of transplant rejection and alleviation of allergic responses with fewer side effects than with conventional immunosuppressive agents.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit under 35 U.S.C. § 119(e) of U.S.Provisional Patent Application No. 60/431,851 filed Dec. 9, 2002, thedisclosure of which is hereby incorporated herein by reference.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of Grant No.N1DDK 38016-12 awarded by the National Institutes of Health.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to inhibition of proliferationand function of lymphocytes and other cells of lymphoid origin whichcontain the Janus tyrosine kinase (Jak3). More particularly theinvention relates to therapeutic and testing methods using chemicalagents which block lymphocyte function, especially regulation of immuneactivity. Still more particularly, the invention relates to selectivelydisrupting Janus tyrosine kinase 3 (Jak3) mediated cell activities andcell proliferation.

2. Description of Related Art

The efficacy of therapeutic strategies in use today to combat organallograft rejection is severely limited due to dependence onimmunosuppressive drugs that produce potent side effects. Currentclinical immunosuppressive regimens are dominated by theserine-threonine phosphatase calcineurin (CaN) inhibitors cyclosporin A(CsA) and tacrolimus (FK506),¹ which act as T-cell modifiers by blockingT-cell progression through the early G₁ stages of the cell cycle.^(1,2)Undesirable side effects associated with those drugs includenephrotoxicity, neurotoxicity, diabetes mellitus, hyperlipidemia,hypertension, hirsutism, and gingival hyperplasia.³ A newer drug,rapamycin (RAPA), which targets the serine-threonine kinase mammaliantarget of RAPA (mTOR), can also manifest mucosal ulcers,lymphoproliferative disorders, hypokalemia, and increases in low densitylipoproteins, cholesterol, and triglycerides.⁴ A serious drawback of theclinically approved drugs is that they do not yield permanent acceptanceof allografts, and therefore they need to be continuously delivered tothe patients.

Recent therapeutic strategies to combat organ allograft rejection havefocused on T-cell signaling pathways and the molecules that comprisethem. T-cell signaling cascades and their potential role inimmunosuppression and potentially for the induction of transplantationtolerance are described by Kirken and Stepkowski.⁵ Complete activationof T-cells requires three threshold-limited sequential signals.⁶

Signal 1 delivered by antigens that engage a specific T-cell receptor(TCR) is then followed by signal 2 delivered by a B7/CD28 interaction.Within seconds to minutes after TCR engagement, the CD3ζ chain istyrosine (Tyr) phosphorylated during the autoactivation of Zap70, Lck,and Fyn protein Tyr kinases.⁷⁻⁹ Concomitantly, calcium (Ca²⁺)mobilization triggers catalytic activation of CaN phosphatase todephosphorylate nuclear factor of activated T-cell (NFAT)—a necessarystep for NFAT to translocate to the nucleus and bind discrete DNAbinding elements within the promoter of the interleukin (IL)-2 gene.¹⁰Signals 1 and 2 are critical for the synthesis and secretion of IL-2,which, in concert with other T-cell growth factors (TCGFs) such as IL-4,-7, -9, -13, -15 and -21, deliver signal 3 through cytokine receptors, anecessary step required to drive clonal expansion of T-cells.¹¹ Thesecytokine receptors share a common γ chain (γ_(c)) that when combinedwith a unique α-chain for each cytokine deliver intracellular signalsvia Janus tyrosine (Tyr), Jak1 and Jak3, as well as activate signaltransducers and activators of transcription (Stat)1, Stat3, Stat5a/b andStat6.¹¹⁻¹⁸

The CaN enzyme (participating in the signal 1 pathway in T-cells) andthe mTOR enzyme (participating in the signal 3 pathway in T-cells) areubiquitously expressed in various tissues throughout the body. Thisseverely limits the efficacy of their inhibitory drugs such as CsA,FK506 and RAPA for T-cell specific targeting. RAPA is the only effectivesignal 3 inhibitor that has been clinically approved to date²⁴. Unlikeother signaling pathway molecules that serve as candidate targets fortherapeutic intervention, Jak3 expression shows a limited pattern oftissue expression and is compartmentalized to T-cells, B-cells, naturalkiller (NK) cells and monocytes, or in general terms to cells of immuneorigin.

Due to its primary localization to lymphoid-type cells, Jak3 holdspromise as a unique molecular and therapeutic target for ablating anumber of immune-derived diseases.¹⁹⁻²¹ This enzyme is almostexclusively associated and activated via γ_(c), and therefore geneticdisruption of Jak3 or γ_(c) is manifested as severe combinedimmunodeficiency disease.²² The reasons for this profound immunesuppression is due to Jak3's critical role in T-cell development andrecruitment by a family of TCGFs as mentioned above. Because Jak3 isassociated with the receptor component and membrane proximal, alldownstream signals emanating from these receptors, including Stat andmitogen activated protein kinase (Mapk) cascades would be activated.Thus, disruption of Jak3 subsequently blocks all signals mediated byTCGF and hence their ability to regulate gene transcription within thesecells. However, if one could control the inhibition of this unique andredundant signaling pathway, favorable regulation of immune activityshould be attainable as observed in patients and mice defective in thesegenes. Moreover, targeting this pathway would, in theory, also inhibit apopulation of activated and proliferating T-cells responsible forrejection that are not responsive to CsA²¹.

Efforts to identify inhibitors that specifically target Jak3 inlymphocytes are hampered by the fact that the few reported drugs thatinhibit Jak3 also inhibit a plethora of other tyrosine kinases that arerequired for routine cell function in many body tissues. Indeed theseprotein tyrosine kinases are fundamentally important for transducingextracellular signals from cell surface receptors to the nucleus,subsequently regulating growth, differentiation and function in celltypes other than lymphocytes.

U.S. patent application Publication 2002/0042513 (Uckun et al.)describes certain quinazoline compounds that are selected on the basisof their estimated docking affinity using a Jak3 homology model based onstructural homology to the insulin receptor tyrosine kinase. The abilityof some quinazoline compounds to treat or prevent transplantcomplications, autoimmune induced diabetes, or to prolong allograftsurvival were evaluated.

U.S. patent application Publication No. 2002/0032204 (Moon et al.)describes certain Mannich base prodrugs of certain3-(pyrrol-2-ylmethylidene)-2-indolinone derivatives that modulate thecatalytic activity of receptor tyrosine kinases (RTKs), non-receptorprotein tyrosine kinases (CTKs) and serine/threonine protein kinases(STKs). These prodrugs are said to be useful for treating many diseasesmediated by abnormal protein kinase activity. The disclosed compoundsare said to modulate RTK, CTK and/or STK mediated signal transductionpathways as a therapeutic approach to cure many kinds of solid tumors.Other Mannich base compounds have been described and evaluated forcytotoxicity and anticancer properties.^(34,35) Certain Mannich bases ofconjugated styryl ketones with antifungal and antineoplastic propertiesare the subject of U.S. Pat. No. 6,017,933.

Recently, two agents that show selectivity for Jak3 have beenidentified.^(21,24,25) One agent denoted as AG-490 is a tyrphostinfamily member and a derivative of benzylidene malononitrile, which hasthe structural formula:

Another is PNU156804, which is a congener of the toxic parent compoundundecylprodigiosin, and has the structural formula:

Both AG-490 and PNU156804 are competent to inhibit T-cell proliferationmediated by TCGFs and Jak3 autokinase activity, while having limitedeffects on unactivated T-cells that fail to express Jak3. It was foundthat neither of those two agents affects T-cell receptor activationcascade intermediates including p56Lck or Zap70 tyrosinekinases.^(23,25)

In one study AG-490 treatment reduced graft infiltration of mononuclearcells (GICs) and Stat5a/b DNA binding of ex vivo IL-2 stimulated GICs,but failed to affect IL2Rα expression as judged by ribonucleaseprotection assays. Thus, it was concluded that inhibition of Jak3prolongs allograft survival and also potentiates the immunosuppressiveeffects of CsA, but not RAPA. It was also found that AG-490 does notinhibit other tyrosine kinase family members Lck, Lyn, Btk, Syk, Src,Jak1 or Tyk2 kinases, while it does exert similar effects on its closestrelated family member Jak.²⁴ Adverse side effects of AG-490 precluderoutine clinical use for immunosuppressive therapy.

PNU156804, on the other hand, displayed greater specificity byinhibiting Jak3 mediated T-cell growth by IL-2 as compared to othergrowth factors (prolactin) that use Jak2. Kinase assays showed thatPNU156804 preferentially inhibited Jak3 autophosphorylation, as comparedwith Jak2, as well as shared intermediate effector molecules such as theStat5 pathways.²⁵ In that study, it was shown that PNU156804 prolongsallograft survival and acts synergistically with CsA but additively withRAPA. It was also established that PNU156804 preferentially disruptsJak3 (compared with Jak2 autokinase activity), thereby selectivelyinhibiting γ_(c)-driven T-cell clonal expansion. Current models holdthat Jak3 is an upstream activator of mTOR. Since Jak3 is expressed inimmune cells, inhibition of Jak3 will block mTOR activation without theadverse effects currently associated with RAPA. Moreover, synergybetween CsA (blocking G₀-G₁ transition) and PNU156804 (blocking G₁-Sprogression) offers a novel strategy for immunosuppression by blockingsequential activation signals thereby requiring lower dosages of eachdrug while maintaining a beneficial therapeutic effect.²⁵ PNU156804 hassubsequently proven to be too toxic for therapeutic use in humans,however.

While some currently available drugs have shown promise in blockingacute rejection, the problems of chronic graft destruction and permanentallograft acceptance (e.g. transplantation tolerance) in the absence ofcontinuous immune suppression remain unabated. Therapeutic methods thatadequately address these problems and pharmaceuticals that avoid adverseside effects are needed. Toward those goals, great strides have beenmade in understanding T-cell signal transduction and in devisingstrategies for targeting certain molecules in the signaling pathways.There is an urgent need for agents that selectively or specificallyinhibit molecules unique for signal 3 pathways of T- and B-lymphocytesactivated by TCGFs. Such agents have great potential for blocking clonalexpansion of T-cells without affecting other cells. As discussed above,Jak3 represents a unique molecular target in the signal 3 pathway forregulating unwanted immune responses such as host-versus-graft andgraft-versus-host disease.

SUMMARY OF PREFERRED EMBODIMENTS

The present invention seeks to overcome certain drawbacks inherent inthe prior art by providing new ways to disrupt or inhibit functionand/or proliferation of any cell type expressing Janus tyrosine kinase 3(Jak3), preferably those of lymphoid or myeloid origin (“lymphoid ormyeloid cells”), including T-cells, B-cells, natural killer (NK) cells,monocytes, macrophages and dendritic cells. Accordingly, in certainembodiments of the present invention, disruption or inhibition oflymphocyte function and/or proliferation is accomplished by treating thecell with certain compounds, preferably Mannich bases, to obtaintherapeutic immunosuppression. In certain embodiments of the presentinvention, in vivo and in vitro therapeutic and testing methods areprovided that employ certain Mannich base compounds, or other compounds,which were previously unknown or unrecognized as being capable of actingas immunosuppressive agents that preferentially disrupt Jak3 whileleaving other widely disseminated protein tyrosine kinases virtuallyunaffected. When employed therapeutically, these agents also avoidentirely, or at least to some extent, the serious side effects commonlyassociated with conventional immunosuppressants in use today. Suchmethods are expected to be clinically useful in mitigating organtransplant rejection, in promoting the remission of autoimmune diseases,airway hypersensitivity (e.g. asthma), allergy, and in inhibitingproliferation of Jak3-dependent leukemia and lymphoma tumors, as well asother Jak3-dependent disorders in cells of lymphoid or myeloid originwhich express Jak3.

Accordingly, in some embodiments of the present invention, an in vitromethod of inhibiting lymphoid or myeloid cell proliferation and/oractivity is provided in which the lymphoid or myeloid cell, such as a Tlymphocyte, monocyte or a dendritic cell, comprises or expresses Jak3.The method comprises culturing the cells in the presence of a compoundcapable of selectively inhibiting Jak3. In some embodiments, a compoundis employed, having formula (I)

wherein R₁ is H, ═CH₂, CH₂N(CH₃)₂, CH₂SC(O)CH₃, CH₂SC₆H₅,CH₂SCH₂-(4-C₆H₄OCH₃), CH₂SC(O)C₆H₅, or CH₂N(CH₂CH₃)₂; R² is O; and R³ isCH₂N(CH₃)₂, CH₂N(CH₂CH₃)₂ and CH₂—(N-morphyl). In a preferredembodiment, the compound is 649641P (NC1153), having formula (I) whereinR1 and R3 are each CH₂N(CH₃)₂. In another preferred embodiment thecompound is the meso stereoisomeric form of 649641P (NC1153), denoted asWP938.

In certain embodiments, a method of inhibiting lymphoid or myeloid cellfunction and/or proliferation is provided which comprises contacting alymphoid or myeloid cell expressing Jak3 with at least one compound offormula (II)

wherein n is 1, 2, 3, 4 or 6; R₁ is H, ═CH₂, or CH₂N(CH₃)₂; and R³ isCH₂N(CH₃)₂, or a salt of said compound, at a concentration effective toselectively inhibit the activity of said Jak3.

In certain embodiments, a method of inhibiting lymphoid or myeloid cellfunction and/or proliferation is provided which includes contacting alymphoid or myeloid cell expressing Jak3 with at least one compound offormula (III)

wherein n is 1 or 2; R₁ is H, or CH₂N(CH₃)₂; and R³ is CH₂N(CH₃)₂, or asalt of said compound, at a concentration effective to selectivelyinhibit the activity of said Jak3.

In some embodiments of a method of inhibiting lymphoid cell functionand/or proliferation, as described above, the lymphoid cell is anactivated T-cell, and the method includes interfering with the signal 3pathway such that cell division is blocked. In some embodiments, thelymphoid cell is contacted with the compound at a concentrationeffective to selectively inhibit Janus tyrosine kinase 3 andsubstantially ineffective to inhibit the activity of other proteintyrosine kinases. In some embodiments, Jak3 activity is inhibited inkinase assays at least 50 fold more than Jak2 activity in a populationof lymphocytes, such as T-cells. In some embodiments, the methodincludes choosing one or more compound that is incapable or less capableof inhibiting Jak2 and Stat5a/b activation by prolactin (PRL) at aconcentration sufficient to inhibit Jak3 and Stat5a/b activated by IL2.

In still other embodiments of the present invention, an in vitro testingmethod to aid in identifying substances that are useful as therapeuticimmunosuppressants is provided. Such method may comprise: (a) obtaininga population of quiescent Jak3 dependent T lymphocytes in cell culturemedium; (b) optionally, pretreating the quiescent T lymphocytes with acytokine to stimulate the lymphocytes to proliferate; (c) treating thequiescent or stimulated lymphocytes from step (a) or (b) with any of thecompounds, or their salts, having formula (I), (II) or (III), as setforth above; (d) culturing the lymphocytes from step (c) under cellgrowth promoting conditions; (e) assessing the extent of cellproliferation following step (d); (f) optionally, assessing theinhibitory effect of said compound on Jak2-dependent T lymphocyteproliferation; (g) optionally, assessing cytotoxicity of said compound;(h) determining from the assessments from step (e) and from (f) and (g),if present, that significant inhibition of Jak3-dependent lymphocyte, orother Jak3 expressing cell type, proliferation, not attributable tocytotoxicity of the compound, suggests that the compound has potentialas a candidate drug for therapeutic use in vivo as a T-cell mediatedimmunosuppressant and/or as an inhibitor of T-cell proliferation; and(i) optionally, comparing the assessments from steps (e) and (f), and,if the inhibitory effects assessed in step (f) are significantly lessthan the inhibitory effects assessed in step (e), determining from saidcomparison that said compound is selective to at least some extent forinhibiting Jak3 activity compared to inhibiting Jak2 activity, oranother kinase.

In accordance with another embodiment of the present invention, an invivo method of suppressing an undesired function of a cell in amammalian subject is provided, wherein the cell comprises Jak3. Themethod includes contacting the cell with at least one of the compoundshaving formula (I), (II) or (III) as set forth above, or a metabolite orderivative thereof, in an amount effective to interfere with the signal3 pathway in the cell and thereby inhibit cell function. The contactingcomprises administering to the subject a therapeutically effectiveamount of a pharmaceutical composition containing at least one suchcompound, or mature form of the compound such as an active metabolite,or a precursor of said compound capable of being converted in the bodyof the subject to said compound, or a pharmaceutically acceptable saltof any of those, in a pharmaceutically acceptable carrier, to inhibitJak3-dependent cell function. The administering may be carried outcontinuously or periodically. In some embodiments the Jak3-containingcell is a T-cell and the amount of the pharmaceutical compositionadministered is effective to block cell division in the T-cell. Incertain preferred embodiments the nephrotoxicity of the compound,metabolite, derivative, or precursor is less than that of cyclosporin A.

In accordance with certain embodiments of the present invention, isprovided a method of therapeutically treating a mammalian subject tosuppress an undesired immune response, wherein the subject isexperiencing or is at risk of experiencing an undesired immune response.This method includes carrying out an above-described method ofsuppressing an undesired lymphocyte function in a mammalian subjectwherein the therapeutically effective amount of the pharmaceuticalcomposition mitigates or prevents said undesired immune response. Incertain embodiments, the method further includes administering to thesubject a therapeutically effective amount of an immunosuppressive agentother than a Jak3 inhibitor; for example, cyclosporin A or FK506. Thisoffers the advantage of inhibiting T-cell function by blocking T-cellactivation via the signal 1 pathway and also by blocking cell divisionof the activated T-cell via interfering with the signal 3 pathway.

In accordance with certain embodiments of the present invention, amethod of mitigating organ transplant rejection in a mammaliantransplant recipient is provided which comprises carrying out anabove-described method of suppressing an undesired lymphocyte functionin a mammalian subject effective to suppress a T-cell mediated immuneresponse to the transplanted organ whereby rejection of the organ ismitigated or arrested.

In accordance with certain embodiments of the present invention, amethod of mitigating acute allograft rejection in a mammalian allograftrecipient is provided which includes carrying out an above-describedmethod of suppressing an undesired lymphocyte function in a mammaliansubject effective to suppress a T-cell mediated anti-allograft immuneresponse whereby acute rejection of the allograft is mitigated orprevented. In some embodiments, a method for prophylaxis of chronicallograft rejection is provided which includes continuous or periodicadministration of the Jak3 inhibitor composition.

In accordance with certain embodiments of the present invention, amethod is provided for inducing transplantation tolerance in a mammaliantransplant recipient. The method includes carrying out anabove-described method of suppressing an undesired lymphocyte functionin a mammalian subject effective to suppress a T-cell mediatedtransplant rejection response.

In accordance with certain embodiments of the present invention, amethod of promoting remission of an autoimmune disease in a mammaliansubject suffering from said disease is provided. The method comprisescarrying out an above-described method of suppressing an undesiredlymphocyte function in a mammalian subject effective to suppress aT-cell mediated autoimmune response in said subject whereby autoimmuneattack on the subject's native tissue mediated by endogenousJak3-dependent T-cells is diminished or arrested.

In accordance with certain embodiments of the present invention, amethod of mitigating airway hypersensitivity in a mammalian subjectsuffering from said hypersensitivity is provided. The method includescarrying out an above-described method of suppressing an undesiredlymphocyte function in a mammalian subject effective to suppress aT-cell mediated hypersensitivity response in the subject wherebyhypersensitivity of airway tissue in the subject is diminished orarrested.

Some embodiments of the present invention provide a method of mitigatingallergy in a mammalian subject suffering from said allergy whichincludes carrying out an above-described method of suppressing anundesired lymphocyte function in a mammalian subject effective tosuppress a T-cell mediated allergic response in the subject whereby anallergic reaction in the subject is diminished or arrested.

Still other embodiments of the present invention provide a method ofinhibiting proliferation of a Jak3-dependent leukemia or lymphoma whichcomprises carrying out an above-described method of suppressing anundesired lymphocyte function in a mammalian subject suffering fromleukemia or lymphoma. In preferred embodiments, the compound or itsmetabolite or derivative is capable of selectively or specificallyinhibiting Jak3 activity compared to inhibition of the activity of otherkinases (e.g., Jak2). The amount of the pharmaceutical composition iseffective to inhibit or block proliferation of leukemia or lymphomacells.

In additional embodiments of the present invention, in vitro methods areprovided which are useful for elucidating the biological processesassociated with T-cell mediated immune responses and for identifying newimmunosuppressive drugs. In some embodiments, an in vitro method to aidin identifying a new immunosuppressive drug is provided which comprises(a) testing a compound of interest for activity for disrupting T-cellfunction by contacting a T-cell comprising Jak3 with a compound ofinterest over a range of concentrations and determining whether thecompound inhibits Jak3 activity at one or more concentration within therange; (b) comparing the Jak3 inhibitory activity of the compound ofinterest to that of a compound of formula (I), (II) or (III) havingknown Jak3 inhibitory activity, preferably 649641P (NC1153); and (c)using the results of such testing and comparing to determine whether thecompound of interest is a candidate drug for in vivo use as atherapeutic immunosuppressive agent. In some embodiments the method alsoincludes (d) testing the compound of interest for inhibitory activity ofone or more other kinase (e.g., Jak2); (e) comparing the Jak3 inhibitoryactivity of the compound of interest to its inhibitory activity, if any,of one or more other kinase; and (f) using the comparisons to identifythe compound of interest as a selective Jak3 inhibitor.

In another embodiment of the present invention, in vivo testing methodsare provided which employ certain Jak3 selective or specific inhibitors.Such methods will be useful for studying T-cell mediated immuneresponses in animal models, and compounds such as 649641P (NC1153),WP938, and others identified in FIGS. 14B-39B may serve as a standardfor comparing the activity of candidate Jak3 specific inhibitors. Onesuch method for testing a candidate immunosuppressive drug for itseffect on allograft survival includes: (a) implanting an allograft takenfrom a suitable donor animal into a suitable recipient animal; (b)maintaining basic nutrition and health promoting conditions for theanimals; (c) administering the candidate drug to each of at least oneanimal, to provide a treated recipient or group; (d) administering to atleast one animal the compound as defined in claim 1, wherein R¹ and R³are each CN(CH₃)₂ and R² is), to serve as a positive control group; (e)optionally, leaving at least one recipient animal untreated, to serve asan untreated control recipient or group; (f) determining allograftsurvival time of each allograft in each recipient; (g) performinghistological examination of each allograft and assessing candidate drugrelated structural damage to each allograft, as applicable; (h)comparing the allograft survival time and the candidate drug inducedhistological structural changes in each allograft; and (i) using thecomparisons from (h), determining that enhanced graft survival time andlack of drug induced structural damage to the drug treated allograftscompared to the allograft(s) from the untreated control recipient(s) orcompared to the allograft(s) from the positive control recipient(s) isindicative that the candidate drug is likely to be effective when usedtherapeutically in vivo as an immunosuppressive agent. In someembodiments, the method also includes determining that the candidatedrug is capable of selectively inhibiting Jak3 dependent T-cellproliferation in vitro.

In certain other embodiments, in vivo methods of evaluating a candidatedrug for in vivo immunosuppressive potential are provided. The candidatedrug is preferably first identified as being capable of selectivelyinhibiting Jak3 dependent T-cell proliferation in vitro. The methodincludes (a) implanting an allograft taken from a suitable donor animalinto a suitable recipient animal; (b) maintaining basic nutrition andhealth promoting conditions for the animals; (c) administering thecandidate drug to each of at least one animal, to provide a treatedrecipient or group; (d) administering 649641P (NC1153) to each of atleast one animal, to serve as a standard recipient or group; (e)preferably, leaving at least one recipient animal untreated, to serve asan untreated control recipient or group; (f) determining allograftsurvival time of each the allograft in each recipient; (g) performinghistological examination of each the allograft and assessing drugrelated structural damage to each allograft, as applicable; and (h)comparing the allograft survival time and the drug induced histologicalstructural changes in each allograft; and (i) using the comparisons from(h), determining that enhanced graft survival time and lack of druginduced structural damage to the drug treated allografts compared to theallograft(s) from the untreated control recipient(s) or compared to theallograft(s) from the positive control recipient(s) is indicative thatthe candidate drug is likely to be effective when used therapeuticallyin vivo as an immunosuppressive agent. These and other embodiments,features and advantages of the present invention will become apparentwith reference to the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawing(s) will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1A is a graph showing the dose-dependent effect of 649641P (NC1153)on γc/Jak3-dependent PHA-activated human T cell proliferation culturedin the absence or presence of 1 nM human IL-2 (▪), IL-4 (•), or IL-7 (▴)normalized to untreated controls.

FIG. 1B is a graph showing the inhibitory effect of 649641P (NC1153) onJak2 versus Jak3 dependent rat T cell proliferation when cultured in thepresence of the Jak2 activator (PRL[∘]) or the Jak3 activator (IL-2[▪]).

FIGS. 2A-2C are Western blots showing inhibition or no inhibition by649641P (NC1153) on phosphorylation. FIG. 2A shows IL-2 activated Jak3tyrosine phosphorylation in human YT cells.

FIG. 2B shows the effect of 649641P (NC1153) on IL-2 activated Stat5atyrosine phosphorylation in human YT cells. FIG. 2C shows the effect of649641P (NC1153) on IL-2 activated Stat5b tyrosine phosphorylation in YTcells.

FIG. 3 is a Western blot showing the effect of 649641P (NC1153) onIL-2-activated p44/42 ERK1/2 phosphorylation in PHA-activated T-cells.

FIG. 4 is a Western blot showing no effect of 649641P (NC1153) onactivated Fyn and Lck in YT cells.

FIG. 5 is a graph showing the combination index for a range of CsA to649641P (NC1153) ratios for survival of Lewis to ACI recipient rat heartallografts.

FIGS. 6A-E are photomicrographs (200× magnification) showing the effectsof 649461P (NC1153), RAPA and CsA on rat kidney structure. FIG. 6A is649461P (NC1153). FIG. 6B is RAPA.

FIG. 6C is CsA. FIG. 6D is shows the combined effects of CsA and RAPA(sirolimus or SRL). FIG. 6E shows the combined effects of CsA and649641P (NC1153).

FIGS. 7A-D are graphs showing that 649641P (NC1153) specificallyinhibits growth of Jak3 containing T-cells. FIG. 7A is a bar graphshowing that proliferation of PHA-activated human T cells was blocked bythe indicated NCI agents following stimulation with IL-2. FIG. 7B is aFACS analysis of PHA-activated T-cell blasts that were treated without(heavy line) or with 50 μM NC1153 (light line) overnight and stained forIL2R-α, -β, and -γchains. FIG. 7C is a graph of cell growth inhibitionover a range of NC1153 concentration in non-Jak3 expressing Jurkat cells(black diamonds) and in Jak3 containing PHA activated T-cells (openboxes). FIG. 7D is a graph of cell growth inhibition versus NC1153concentration in T-cells stimulated by cytokines that utilize Jak3 andthe common gamma chain.

FIG. 8 is a bar graph showing that Jak3 autokinase activity is directlyblocked by 649641P (NC1153) based on in vitro analysis. ImmunopurifiedJak3 was assayed for Jak3 autokinase activity and tested byphosphotyrosine Western blot in the absence or presence of 100 μM ATPand/or drug and compared to controls. 649641P (NC1153) showed an IC₅₀ ofapproximately 2.5 μM, which parallels the proliferation data of FIGS. 1Aand B.

FIGS. 9A-C demonstrate 649641P (NC1153) selectivity. FIG. 9A is anelectrophoretic mobility shift assay (EMSA) autoradiograph showing that649641P (NC1153) inhibits Jak3 driven transcription factor-Stat5a/b inPHA activated T-cells treated with increasing concentrations of 649641P(NC1153) in a dose dependent manner (upper panel). Non-Jak3 mediatedNfκB activation by TNF-α was not affected within the same treatment set(lower panel). FIG. 9B is a Western blot autoradiograph demonstratingthat 649641P (NC1153) fails to inhibit closely related Jak2/Stat5asignaling pathway. Prolactin [PRL] (+) or (−) indicates whether thecells were stimulated with prolactin with Jak2 activation.Phosphotyrosine Western blots detect Jak2-Stat5 activation but noinhibition by 649641P (NC1153). FIG. 9C is a bar graph demonstratingthat 649641P (NC1153) fails to affect the activity of multiple kinasesother than Jak3. 649641P (NC1153) was tested at 10 (open bars) or 50 μM(filled bars) to block growth factor tyrosine kinases (FGFR3 andPDGFRα), Src family tyrosine kinases (Src, Fyn, Lck, Yes, Zap70) orserine threonine kinases (PKC and PKA) phosphorylation of a substrate.The activity of the control is plotted as a dashed line.

FIGS. 10A-D illustrate the in vivo effects of NC1153 on allograftsurvival. FIG. 10A shows graft survival in ACI rat recipients of Lewis(LEW) kidney allografts treated for 7 days with 649641P (NC1153)delivered by daily i.v. injections (left panel) or by oral gavage (rightpanel). FIG. 10B shows graft survival in similar recipients treated for14 days with 649641P (NC1153) delivered by daily oral gavage. FIG. 10Cshows graft survival in similar recipients treated for 7 days andthereafter 3×/week up to 90 days with 160 mg/kg NC1153 delivered bydaily oral gavage. FIG. 10D demonstrates the synergistic effect ofNC1153 delivered by daily oral gavage with CsA in ACI rat recipients ofLEW kidney allografts treated for 7 days. 649641P (NC1153) alone (darkbars). CsA alone (open bars). 649641P (NC1153) and CsA (light bars).

FIGS. 11A-F are graphs of assay results demonstrating that 649641P(NC1153) is not nephrotoxic and does not affect lipid metabolism,evaluated by serum creatinine levels (FIG. 11A) serum creatinineclearance (FIG. 11B), serum cholesterol (FIG. 11C), triglycerides (FIG.11D), LDL-cholesterol (FIG. 11E), and HDL-cholesterol (FIG. 11F).Results are displayed in mg/dL. Histological appearance was as shown inFIGS. 6A-E.

FIGS. 12A-B are analogous to FIGS. 10A-D, except that they show theresults with the meso stereoisomer of 649641P (NC1153) designated WP938(shown in FIG. 18B) that was tested for allograft survival in ACIrecipients of LEW kidney allografts. FIG. 12A shows mean survival ofuntreated, CsA alone treated, and WP938 alone treated rats. FIG. 12Bshows comparison of one dose CsA alone, one dose WP938 alone incomparison with the same doses of CsA/WP938 combination; CI value of0.44 documents synergistic interaction.

FIGS. 13A-F show the results of toxicity assays for WP938 alone or incombination with CsA. FIG. 13A indicates serum creatine levels. FIG. 13Bindicates creatinine clearance. FIG. 13C indicates cholesterol levels.FIG. 13D indicates triglyceride. FIG. 13E indicates HDL levels. FIG. 13Findicates LDL levels.

FIGS. 14A,B-39A,B show the chemical formulas of a number of compoundsand their activities for inhibiting Jak3-dependent or Jak-3 independentproliferation of T-cells in an in vitro assay. (A) IL-2 stimulated(light circles); PRL stimulated (dark circles). (B) The correspondingstructural formula of each compound (shown as a salt).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In studies described herein it is confirmed that a biochemicalintermediate—the enzyme Janus tyrosine kinase 3 (Jak3)—is critical formature T-cell activation, function and allograft rejection. Certaincompounds identified herein, especially those classified as Mannichbases, which selectively inhibit Jak3, may offer therapeutic advantagesover conventional immunosuppressive drugs such as CsA, FK506, and RAPA.As discussed in the background section above, RAPA inhibits mTOR,whereas CsA and FK506 blocks CaN, and both of those target moleculesdisplay ubiquitous expression profiles causing potent toxic sideeffects. In contrast, Jak3 expression is confined exclusively to thelymphoid compartment, including T and B lymphocytes.

Initially, a series of tests were performed seeking to identify andcharacterize antagonists of Jak3, which thereby inhibit an entire familyof TCGF-dependent pathways. A group of Mannich-base and other compounds,were screened for selective Jak3 inhibitory activity over a range ofconcentrations. Those which demonstrated some measure of selectiveinhibition of IL-2 stimulated (i.e., Jak3-dependent) T-cellproliferation, compared to prolactin (PRL) stimulated (i.e.,Jak2-dependent) T-cell proliferation, along with some structurallysimilar compounds, are shown by their structural formulas in FIGS.14B-39B. The corresponding inhibitory activity of each compound is shownin FIGS. 14A-39A. FIG. 22A shows the results of assays similar to thoseof FIG. 21A, but with a slightly different purity preparation of thesame compound as FIG. 21B. In addition to Mannich bases, structurallysimilar compounds (FIGS. 25B and 26B) are included among the compoundstested. The following materials and general methods were used, except asotherwise stated in the Examples. A representative compound, 649641P,also referred to herein by its NCI drug database number NC1153, and ameso stereoisomer shown in FIG. 18B (denoted WP938), which demonstratedidentical selective Jak3 inhibition in vitro, were tested further forability to prolong allograft survival alone or in combination with CsA,as well as for drug-induced toxicities.

General Methods and Materials

Cell culture and treatment. The rat T-cell line Nb2-11c, originallydeveloped by Dr. Peter Gout (Vancouver, Canada), was grown in RPMI-1640with 10% fetal calf serum (Intergen, cat. no. 1020-90), 2 mML-glutamine, 5 mM HEPES, pH 7.3, and penicillin-streptomycin (50 IU/mland 50 μg/ml, respectively), at 37° C./5% CO₂. Freshly explanted normalhuman T lymphocytes purified by isocentrifugation (Ficoll®; EM Science,Gibbstown, N.J.) were phytohemagglutinin (PHA)-activated for 72 hours aspreviously described.²³ T lymphocytes were made quiescent by washing andincubating for 24 hours in RPMI-1640 medium containing 1% fetal calfserum before exposure to cytokines. Next, cells were treated withvarying concentrations of 649641P (NC1153) as described below in thefigure descriptions. The Mannich base 649641P (NC1153) was generouslyprovided by Dr. Jonathan Dimmock College of Pharmacy, University ofSaskatchewan, Saskatoon, Saskatchewan, Canada. All cells were thenstimulated with 1 nM recombinant human IL-2 (Hoffman-LaRoche, Basel,Switzerland), IL4 or IL7 (PeproTech), or ovine prolactin (PRL) suppliedby the National Hormone and Pituitary Program, National Institute ofDiabetes, Digestive, and Kidney Disease (Bethesda, Md.), at 37° C. Cellpellets were frozen at −70° C.

Proliferation assays. Quiescent human primary T-cells, YT or rat Nb2-11cT-cells (5.0×10⁴/well) were plated in flat-bottom, 96-well microtiterplates in 200 μl of quiescent media in the absence or presence of 1 nMIL-2, -4, -7 (PeproTech, Rock Hill, N.J.), or PRL. Next, cells weretreated for 16 hours with the Mannich base drug and then pulsed for 4hours with [³H]-thymidine (0.5 μCi/200 μl) and harvested onto fiberglassfilters. [³H]-thymidine incorporation was analyzed by liquidscintillation counting as previously described,²³ or using standardtechniques that are well known in the art.

Solubilization of membrane proteins, immunoprecipitation, and Westernblot analysis. Frozen cell pellets were thawed on ice and solubilized in1% TX-100 lysis buffer (10⁸ cells/ml) and clarified by centrifugation,as previously described.¹⁶ For human T-cells, supernates were incubatedrotating end over end for 2 hours at 4° C. with either 5 μl/mlpolyclonal rabbit antisera raised against peptides derived from theunique COOH-termini of Jak3 (amino acid [a.a.] 1104-1124), carboxyltermini of human Stat5a (a.a. 775-794) or Stat5b (a.a. 777-787).²⁶ Aband immunoprecipitated proteins were captured by incubation for 30minutes with Protein A-Sepharose beads (Pharmacia, Piscataway, N.J.),sedimented for purification, and eluted by boiling in 2×SDS-samplebuffer (20% Glycerol, 10% 2-Mercaptoethanol, 4.6% SDS, 0.004%Bromophenol blue in 0.125 M Tris pH 6.8) for 4 minutes. For phosphoMapkassays, approximately 25 μg of total cell lysate was dissociated inSDS-sample buffer and separated on 10% (all others on 7.5%) SDS-PAGEunder reducing conditions. Proteins were transferred to polyvinylidenedifluoride (Immobilon™; cat. no. 1PVH 00010, Millipore, Bedford, Mass.)as previously described.²⁷ Western blot analysis was performed witheither pAbs, murine anti-phosphotyrosine monoclonal antibodies (mAbs;UBI; 4G10; cat. no. 05-321, Upstate Biotechnology, Inc., Lake Placid,N.Y.), or phospho p44/42 Mapk (New England Biolabs, Beverly, Mass., Catno. 9101). Blots Westerned with the above antibodies, rabbitantiphospho-Erk1/2, and monoclonal pan-Erk (Pharmingen, San Diego,Calif., Cat no. E17120) were diluted 1:1000 in blocking buffer and usedas previously described,²⁷ or employing standard techniques that arewell known in the art. Blots Westerned with rabbit antiphospho-tyrosine(αPY), and monoclonal mouse anti-Fyn or anti-Lck antibodies (BDBiosciences, San Diego, Calif., Cat no. 610163 [Fyn] and 610097 [Lck])were diluted 1:1000 in blocking buffer as previously described²⁷.

Rat Kidney Transplants. Adult male ACI (RT1^(a)) and Lewis (LEW; RT1¹)rats (160-200 g) obtained from Harlan Sprague-Dawley (Indianapolis,Ind.) were cared for according to the guidelines of the Animal WelfareCommittee. Rats were housed in light- and temperature-controlledquarters and given chow and water ad libitum. Kidneys were transplantedheterotopically from LEW donors to ACI recipients using a standardmicrosurgical technique of Ono and Lindsey²⁸. For immunosuppressive drugevaluation, transplant recipients were treated with the Mannich basecompound by daily intravenous (i.v.) injection or oral gavage (p.o.),alone or in combination with CsA or RAPA administered daily by oralgavage. A control group of recipients remained untreated. Somerecipients were treated with CsA or RAPA alone. Graft survival time wasdefined as animal survival of life supporting kidney transplant. Theresults, presented as mean survival time (MST)±standard deviation (SD),were assessed for statistical significance by Gehan's survival test. Inaddition, the interaction between the Mannich base and CsA or RAPA wasevaluated by the median effect analysis.^(29,30) Computer software wasused to calculate combination index (CI) values: CI<1 showedsynergistic, CI>1 antagonistic, or CI=1 additive interactions.³⁰

Histopathologic Evaluation. ACI (RT1^(a)) recipients of LEW (RT1¹)kidney allografts kidney allografts were treated as described in theExamples which follow. At day 7 posttransplant, kidney allografts wereplaced in Bouin's Fixative (Poly Scientific R&D Corp., Bay Shore, N.Y.).Each kidney was sectioned in an identical fashion consisting of singlehorizontal cut followed by three consecutive incisions used to generateslides. Next, another dissection was made followed by three moreconsecutive slices and slides generated. A total number of 12 slides perkidney were stained with hematoxylin-eosin (H&E) as describedpreviously,³¹ or using standard techniques that are known in the art.The degree of rejection was graded in accordance with the standardsestablished by Society of Heart and Lung Transplantation.³² Inparticular, kidneys were fixed in buffered 10% formalin and processedovernight; 3-μ histologic sections were stained with progressivehematoxylin-eosin (H&E) reagents. Two independent pathologists usedsemi-quantitative scales of light microscopic criteria to assess thedegree of vasculopathy, glomerular changes, and tubulo-interstitialdamage in multiple kidney sections. Tubular and glomerular changes wereseparately graded as 0=no changes; 1+=<5%; 2+=5-25%; 3+=26-50%; and4+=>50% involvement. A similar vascular scale included 0=None;1+=minimal; 2+=mild; 3+=moderate; and 4+=severe.

EMSA. Electrophoretic mobility shift assay (EMSA). Drug or vehiclecontrol (DMSO) treated cells were pelleted by centrifugation (20,000×gfor 1 min at 4° C.) and subsequently washed in five volumes of 10 mMHEPES, pH 7.9, 10 mM KCl, 1.5 mM MgCl₂, 0.5 mM DTT, 100 mM PMSF, 5 μg/mlaprotinin, 1 μg/ml pepstatin A and 2 μg/ml leupeptin, centrifuged, thenlysed in the same buffer supplemented with 1% NP-40 and incubated for 20min on ice. The nuclei-containing pellet was resuspended in equalvolumes of low salt buffer (10 mM HEPES, 25% glycerol, 1.5 mM MgCl₂, 20mM KCl, 0.5 mM DTT, 0.2 mM EDTA and protease inhibitors) and high saltbuffer (low salt buffer containing 800 mM KCl). This fraction was thenisolated by centrifugation at 4° C. for 10 min and supernatants saved asnuclear protein extract and stored at −70° C. Gel mobility shift assayswere performed to detect Stat5a/b DNA binding activity using a Stat5 DNAbinding sequence corresponding to the promoter of the β-casein gene(5′-AGATTTCTAGGAATTCAATCC-3′) or an NF-kB binding element(5′-AGTTGAGGGGACTTTCCAGGC-3′). Both probes were end-labeled with[³²P]dATP. Labeled-oligonucleotides were then incubated with 5 μg ofnuclear extracted proteins in 15 μl of binding cocktail (50 mM Tris-Cl,pH 7.4, 25 mM MgCl₂, 5 mM DTT, 50% glycerol) at 4° C. for 2 h. Forsupershift assays, nuclear extracts were pre-incubated with 1 μg ofeither normal rabbit serum or antisera specific to Stat5a, Stat5b, orp50/p65 NFκB (Santa Cruz Biotechnology, Inc., Santa Cruz, Calif.; Catno. sc-1190X and sc-372X, respectively) as indicated in legend at 4° C.for 1 h then incubated with [³²P]-labeled DNA oligonucleotide for 15 minat room temperature. The DNA-protein complexes were resolved on 5%polyacrylamide gels containing 0.25×TBE which were pre-run in 0.25×TBEbuffer for 1 hour at 100 V. Samples were loaded and gels were run atroom temperature for approximately 2 h at 150 V then dried by heatingunder vacuum and exposed to X-ray film (X-Omat, Kodak) at −70° C.

Mannich Bases and Other Compounds. The compound 649641P (NC1153) used ininitial investigations was provided by Dr. Jonathan R. Dimmock of theUniversity of Saskatchewan, Saskatoon, Canada. 649641P (NC1153) andother compounds, including those identified in FIGS. 14B-39B, wereprepared by Dr. Waldemar Priebe of the M.D. Anderson Cancer Center,University of Texas System, Houston, Tex. The compounds described hereinmay be prepared by any suitable methods using commercially availablestarting materials and reagents available from suppliers such as AldrichChemical Co., (Milwaukee, Wis.) and Sigma (St. Louis, Mo.). Standardchemical synthesis techniques and procedures may be employed, as setforth in references such as Fieser and Fieser's REAGENTS FOR ORGANICSYNTHESIS, Volumes 1-17 (John Wiley and Sons, 1991); Rodd's CHEMISTRY OFCARBON COMPOUNDS, Volumes 1-5 and Supplementals (Elsevier SciencePublishers, 1989); ORGANIC REACTIONS, Volumes 1-40 (John Wiley and Sons,1991), March's ADVANCED ORGANIC CHEMISTRY, (John Wiley and Sons, 4thEdition) and Larock's COMPREHENSIVE ORGANIC TRANSFORMATIONS (VCHPublishers Inc., 1989). Additional guidance for synthesizing thecompounds can be found in the periodical literature, for example, thepublications of Dimmock^(34,35), and as set forth below.

The following non-limiting examples are illustrations of thecharacteristics and uses of a representative Jak3-selective inhibitorcompound and are not meant to limit the invention in any way.

EXAMPLE 1 In Vitro Effects of Mannich Base 649641P (NC1153)

The Mannich base denoted 649641P (C₁₈H₃₈C₁₂N₂O; MW 369.41), alsoreferred to as NC1153, as a mixture of its stereoisomers, and having thegeneral formula

was added to T-cells undergoing Jak3-versus Jak2-dependentproliferation, as described above, to test its ability to selectivelyinhibit Jak3. FIG. 1A is a graph showing the effect of 649641P (NC1153)on proliferation of γc/Jak3-dependent PHA-activated human T-cells.Quiescent PHA-activated human T-cells (5.0×10⁴ cells/well) were culturedin the absence or presence of 1 nM human IL-2 (▪), IL-4 (•), or IL-7 (▴)with increasing concentrations of 649641P (NC1153) (ordinate) for 16hours at 37° C. Cells were then pulsed with [³H]-thymidine (0.5 μCi/200μl) for 4 hours and incorporated radiolabeled probe plotted on theabscissa expressed as % inhibition of total cpm from DMSO-treated samplesets (n=6).

FIG. 1B shows the effect of 649641P (NC1153) on proliferation of T-cellscultured in the presence of the Jak2 activator (prolactin; PRL [∘]) orthe Jak3 activator (interleukin-2; IL-2 [▪]). The rat T cell line(Nb2-11c) was chosen because it responds to either PRL/Jak2 or IL-2/Jak3stimulation. Quiescent rat T cells (5.0×10⁴ cells/well) were cultured inthe presence of the Jak2 activator (1 nM PRL ([∘]) or Jak3 activator (1nM IL-2 [▪]), with increasing concentrations of 649641P (NC1153)(ordinate; 0-100 μM) for 16 hours at 37° C. Cells were pulsed with[³H]-thymidine (0.5 μCi/200 μl) during the final 4 hours of the assaythen the DNA-incorporated radiolabeled probe was plotted on the abscissaand expressed as % inhibition of total cpm from DMSO-treated sample sets(n=4). As shown in FIGS. 1A-B, 649641P (NC1153) selectively inhibitsγc/Jak3-dependent but not PRL/Jak2-dependent cell proliferation. Inparticular, although 649641P (NC1153) proved to be equally effective toinhibit Nb2-11c cell proliferation in response to IL-2, IL-4 and IL-7,the same compound was 3-fold more effective for inhibiting Jak3- thanJak2-dependent proliferation.

In FIGS. 2A-C the effect of 649641P (NC1153) on the Jak3/Stat5 signalpathway is shown. Human YT cells were cultured without (a-b) or with(c-i) ascending concentrations (1-100 μM) of 649641P (NC1153) for 2hours and re-challenged for 10 minutes with (+) or without (−) 100 nMIL-2. Cells were immunoprecipitated with anti-Jak3 pAb and Westernblotted with anti-phosphotyrosine mAb, as shown in FIG. 2A, upper panel,and then stripped and re-blotted with anti-Jak3 (FIG. 2A, lower panel).These Western blot experimental results, in which tyrosinephosphorylation of Jak3 was inhibited in a dose-dependent fashion by649641P (NC1153) in human YT cells (1-100 μM), correlate with thoseshown in FIG. 1A. Referring now to FIG. 2B, human YT T-cells were alsocultured without (a and b) or with (c through i) ascendingconcentrations (1-100 μM) 649641P (NC1153) for 2 hrs and re-challengedfor 10 minutes with (+) or without (−)100 nM IL-2. Cells wereimmunoprecipitated with anti-Stat5a pAb and Western blotted withanti-phosphotyrosine mAb (FIG. 2B, upper panel) and then stripped andre-blotted with Stat5a (FIG. 2B, lower panel). In a third test, theresults of which are shown in FIG. 2C, human YT cells were culturedwithout (a-b) or with (c-i) ascending concentrations (1-100 μM) 649641P(NC1153) for 16 hrs and re-challenged for 10 minutes with (+) or without(−)100 nM IL-2. Cells were immunoprecipitated with anti-Stat5b pAb andWestern blotted with anti-phosphotyrosine mAb (FIG. 2C, upper panel) andthen stripped and re-blotted with anti-Stat5b (FIG. 2C, lower panel).

IL-2 also potently activates the Shc/Ras/Raf/Erk pathway via the adapterprotein, Shc, which binds to Tyr338 of the IL-2Rβ chain ultimately todrive T-cell proliferation. FIG. 3 shows the results of a similarexperiment to those described above in which the effect of ascending649641P (NC1153) concentrations on IL-2-mediated p44/42 Erk1/2phosphorylation was investigated. Quiescent PHA-activated T cells weretreated with DMSO (control; lanes a-b) or increasing concentrations(c-i) of 649641P (NC1153) for 2 hours and then stimulated in thepresence of 1 μg at 37° C. for 10 minutes. Cells were lysed and totalcell lysate separated on 10% SDS-PAGE, transferred to PVDF membraneWestern blotted with anti-phospho-p44/42 Erk1/2 (upper panel), thenstripped and reprobed with pan Erk antibody (lower panel). Arrowsindicate location of p44/42 Erk1/2. These results reveal that 649641P(NC1153) blocks IL2-mediated Erk1/2 activation in human T-cells.

YT cells constitutively express activated Fyn and Lck kinases that canbe shown by testing for their tyrosine phosphorylation status. YT cellswere cultured for 2 hours with different concentrations of 649641P(NC1153) (1-100 μM). Cellular extracts were immunoprecipitated withanti-Fyn or anti-Lck antibodies and Western blotted withanti-phosphotyrosine antibodies (αPY), then stripped and re-blotted withanti-Fyn or anti-Lck antibodies. FIG. 4 shows the results of abovedescribed experiment: YT cell extracts immunoprecipitated with anti-Fynand Western blotted with anti-phosphotyrosine antibodies (αPY) (firstrow), and then stripped and re-blotted with anti-Fyn (second row); YTcell extracts were immunoprecipitated (IP) with anti-Lck antibodies andWestern blotted with anti-phosphotyrosine antibodies (αPY) (third row),then stripped and re-blotted with anti-Lck antibodies (forth row). YTcells were cultured with vehicle only (lane a and b) or with ascending649641P (NC1153) concentrations (1-100 μM) (lane c-i). These resultsshow that 649641P (NC1153) does not block the activity of Fyn or Lckkinases.

The foregoing results show that while other inhibitors inhibited Jak3and Jak2 responsive cell growth (IC₅₀ about 10-25 μM), 649641P (NC1153)was more effective by disrupting cell growth with an IC₅₀ about 2.5 μM.Moreover, 649641P (NC1153) effectively inhibited IL4 or IL7 driven cellgrowth at the same concentration (IC₅₀ about 2.5 μM). This agentinhibited tyrosine phosphorylation of Jak3 and its substrates, namelyStat5a/b, adapter protein Shc and Erk1/2, as measured by phospho-Westernblots. 649641P (NC1153) was more effective that the previously describedPNU156804 Jak3 inhibitor, displaying an IC₅₀ about 10 μM. Moreover,although Stat5a/b DNA binding to an oligonucleotide probe was greatlyimpaired by 649641P (NC1153), this compound was specific for thistranscription factor since there was no effect on TNF-α-induced NF-kBDNA binding. The 649641P (NC1153) compound did not inhibit DNA synthesisof non-Jak3 expressing human Jurkat T-cells nor activation of TCRsignaling intermediates Lck or Fyn tyrosine kinases.

EXAMPLE 2 Effect of Mannich Base 649461P (NC1153) on Allograft Survival

To test the in vivo effects, recipients of kidney allografts weretreated with 649641P (NC1153) for 7 days beginning immediately aftertransplantation. ACI (RT1^(a)) recipients of LEW (RT1¹) kidneyallografts were treated by daily i.v. injections for 7 days with 2.5,5.0, 10.0, or 20.0 mg/kg 649641P (NC1153) alone or in combination withoral gavage of 2.5, 5.0, 10.0 or 20.0 mg/kg CsA. The 649641P (NC1153)given alone delivered by i.v. or oral gavage prolonged rat kidneyallograft survival in a dose-dependent fashion, as shown in Table 1.Since 80 mg/kg 649641P (NC1153) p.o. produced similar survivals as 10mg/kg 649641P (NC1153) injected i.v., the oral bioavailability isestimated to be approximately 12.5%. A mean survival time (MST) and SDwas calculated for each group from 5-6 experiments. The combinationindex (CI) values were calculated by the median effect analysis (CI<1shows synergistic, CI>1 antagonistic, and CI=1 additiveinteraction)^(29,30).

TABLE 1 Kidney Allograft Survival (Intravenous Administration of 649641P(NC1153)) 649641P (NC1153) CsA (mg/kg/d) (mg/kg/d) 649641P:CsA i.v. × 7days p.o. × 3 days Ratio MST ± SD P CI — — — 8.8 ± 0.5 — — 2.5 — — 9.5 ±1.5 NS — 5.0 — — 12.2 ± 1.5  0.01 — 10.0  — — 18.8 ± 1.1  0.01 — 20.0  —— 24.8 ± 4.6  0.01 — — 2.5 — 12.6 ± 1.67 0.01 — — 5.0 — 17.2 ± 4.21 0.01— — 10.0 — 21.7 ± 5.32 0.01 — — 20.0 1:1 24.5 ± 4.58 0.01 — 2.5 2.5 —18.8 ± 4.1  0.01 0.56 2.5 5.0 1:2 30.0 ± 8.2  0.01 0.21 2.5 7.5 1:3 30.4± 11.3 0.01 0.27 2.5 10.0 1:4 41.4 ± 9.8  0.01 0.11 5.0 2.5 2:1 20.0 ±2.9  0.01 0.53 5.0 5.0 1:1 27.6 ± 5.3  0.01 0.38 5.0 7.5   1:1.5 33.2 ±11.8 0.01 0.26 10.0  2.5 4:1 25.4 ± 4.0  0.01 0.60 10.0  5.0 2:1 29.8 ±6.5  0.01 0.46

The effect on kidney allograft survival of 649641P (NC1153) alone,administered by oral gavage, or in combination with CsA is shown inTable 2. ACI (RT1^(a)) recipients of LEW (RT1¹) kidney allografts weretreated once daily by oral gavage for 7 days with 40, 80, or 160mg/kg/d. 649641P (NC1153) alone or in combination with oral gavage of2.5, 5.0, 10.0 or 20.0 mg/kg/d CsA. A MST and SD were calculated foreach group from 5-6 experiments. The combination index (CI) values werecalculated.

TABLE 2 Kidney Allograft Survival (Oral Gavage Administration of 649641P(NC1153)) 649641P (NC1153) CsA 649641P: (mg/kg/d) (mg/kg/d) CsA p.o. × 7days p.o. × 3 days Ratio MST ± SD P CI — — — 8.8 ± 0.5 — — 40.0 — — 12.3± 1.26 0.0006 — 80.0 — — 18.6 ± 5.32 0.0015 — 160.0  — — 31.0 ± 3.9 0.0001 — — 2.5 — 12.6 ± 1.67 0.0008 — — 5.0 — 17.2 ± 4.21 0.0009 — —10.0  — 21.2 ± 4.96 0.0001 — — 20.0  — 24.5 ± 4.28 0.0001 — 20.0 10.0 2:1  33.6 ± 10.04 0.0002 0.30 40.0 5.0 8:1 28.8 ± 9.87 0.0006 0.49 40.010.0  4:1  36.0 ± 10.05 0.0001 0.36 80.0 5.0 16:1  36.6 ± 4.72 0.00010.51

The results shown in Table 2 of MST±SD were assessed for statisticalsignificance by Gehan's survival test.

Combination index (CI) values versus CsA/649641P (NC1153) ratioscalculated for the results presented in Table 1, and these data weregraphed as shown in FIG. 5. Considering that CsA oral bioavailability is90%, CsA/649641P (NC1153) ratio of 4:1, 3:1, 2:1 and 1.5:1 showed bettersynergism (CI=0.1-0.27) in comparison to CsA/649641P (NC1153) ratio of1:1, 1:2, or 1:4 (CI=0.38-0.60). The median effect analysis and thecombination index (CI) value were used to calculate the quality ofinteraction between 649641P (NC1153) and CsA. The combination of 649641P(NC1153) and CsA was synergistic, as confirmed by the CI values(0.6-0.1; FIG. 5); 649641P (NC1153)/CsA ratios of 1:2 to 1:4 were themost effective (CI=0.1-0.27; Table 1).

Summarizing the results, 649641P (NC1153) showed dose-dependentprolongation of kidney allograft survival: doses of 20 mg/kg/day 649641P(NC1153) delivered i.v. for 7 days produced a MST of 24.8±6.6 days(p=0.00003 vs. untreated control; MST=8.8±0.5 days) and 240 mg/kg/day649641P (NC1153) delivered p.o. for 7 or 14 days, 47.8±19.59 or >60 days(both p<0.00001). Treatment with CsA alone (2.5, 5, 10, or 20 mg/kg/dfor 3 days) produced dose-dependent effects achieving at the highestdose a MST of 24.50±4.58 days (p<0.0001). The combined treatmentsrevealed a potent synergistic interaction in graft survival incomparison with monotherapy with each agent. For example, although a7-day i.v. administration of 2.5 mg/kg/day 649641P (NC1153) aloneproduced a MST of 9.5±1.4 days, and a 3-day 10 mg/kg/day CsA alone of21.2±5.3 days, two-drug combination prolonged survival to 41.4±9.8 days(p=0.00002). The best results were observed at 649641P:CsA dose ratiosof 4:1 and 2:1, yielding the CI values of 0.11 and 0.27, respectively.It can be concluded that a new and selective Jak3 inhibitor, 649641P(NC1153), has been identified that is immunosuppressive in vivo in akidney allo-transplant model, and exerts marked synergistic effects incombination with CsA.

EXAMPLE 3 Evaluation of 649641P (NC1153) for Nephrotoxicity

For histologic examination, tissue was obtained from ACI (RT1^(a))recipients of LEW (RT1¹) kidney allografts that had been treated asfollows: recipients on low-salt diet for 7 days were treated for 14 dayswith: 10 mg/kg 649641P (NC1153) delivered i.v.; 0.16 mg/kg RAPAdelivered i.v.; 10 mg/kg CsA delivered p.o.; combination of 10 mg/kg CsAp.o. with 0.16 mg/kg RAPA i.v.; or combination of 10 mg/kg CsA p.o. with10 mg/kg 649641P (NC1153) i.v. On day 14 rats were sacrificed andhistology performed on kidneys using H&E staining in accordance withstandard methods. The photomicrographs in FIGS. 6A-E show the effect of649641P (NC1153) alone or in combination with CsA on kidney structure.All photographs are presented at the same 200× magnification. Similarresults were observed in 5 rats per group. Neither 649641P (NC1153)(FIG. 6A) nor RAPA alone (FIG. 6B) showed any significant changes in thekidneys. In contrast, CsA alone (FIG. 6C) caused damage in 30% of tubulias visualized by vacuolization and atrophy. The CsA/RAPA (SRL) groupshowed massive vacuolization in 90% of tubuli with atrophy and pyknoticnuclei (FIG. 6D). In contradistinction to the CsA/RAPA group, kidneysfrom rats treated with the CsA/649641P (NC1153) combination showedchanges similar to those observed in the CsA alone group (FIG. 6E). Inbrief, neither 649641 or RAPA alone caused nephrotoxicity. CsA alone,however, was nephrotoxic, and this effect could be potentiated with RAPAbut not with 649641P (NC1153).

In addition to the histologic studies described above, 649641P(NC1153)-treated animals were also evaluated for the types of toxicitiesthat are typically associated with SRL. In this study, animal treatmentincluded 649641P (NC1153) alone or in combination with CsA. Wistar-Furthrats received 649641P (NC1153) (10 mg/kg/d iv or 40/mg/kg/d per gavage)or SRL (1.6 mg/kg/d per gavage) alone or in combination with CsA (10mg/kg/d per gavage). After 7 days of dietary preconditioning either bysalt depletion (0.05% NaCl) to assess chronic nephrotoxicity or by fatsupplementation (17.7% triglycerides, 5.02% cholesterol), groups of ratsunderwent 7, 14, or 28 day treatment courses (n=6/drug/duration).Differences in creatinine clearance (CrCL); total, low, and high density(HDL) cholesterol (CHOL) fractions; triglycerides (TG); bone marrowcellularity; peripheral blood counts (PBC); and blood chemistries wereassessed by Fishers t test. The results of this study showed that649641P (NC1153) caused weight gain (p=0.0002) and did not enhance theweight loss produced by CsA or SRL. CrCL values were similar foruntreated (2.0 0.1 mL/min) and 649641P (NC1153) alone (1.9 0.1 mL/min),but decreased for SRL alone (1.7 0.1 mL/min; p<0.02), and CsA alone (1.30.1 mL/min; p<0.001). Compared with CsA alone, addition of 648641P didnot further reduce CrCL values (1.38 0.2 mL/min; p=0.68); whereas, SRLmarkedly reduced it (0.9 0.2 mL/min; p=0.03). Compared to untreated ratson a low-salt diet, 649641P (NC1153) decreased serum CHOL (82.0 5.0 vs65.5 9.4 mg/dL; p=0.03) and increased HDL (p=0.004) without changing TGor LDL levels. 648641P did not increase the hypercholesterolemic effectsof CsA (77.5 7.0 alone vs 64.1 12.7 mg/dL in combination), in contrastto SRL+CsA (107.8 8.4 mg/dL; p=0.0005). On a high-fat diet, SRL produceda marked effect on CHOL (689.5 67.4; p=0.00001) and other lipidfractions; CsA, a lesser effect (545.7 95.7 mg/dL; p=0.0002) and 649641P(NC1153), only a modest change (323.8 51.1 mg/dL; p=0.01 vs 237.5 31.4mg/dL) in untreated animals. 649641P (NC1153) had no effect on HDL, LDL,or TG levels. Neither 648641P nor CsA reduced PBC compared to untreatedrats, in contrast to SRL (p<0.04). While SRL/CsA hosts showedhypocellular marrow (30-40% replaced by adipose tissue), 649641P/CsAcohorts showed no significant change from untreated rats. In view ofthese results, it was concluded that 649641P (NC1153) is free ofnephrotoxic and myelotoxic effects with mild lipotoxicity on high-fatchallenge. Since it does not exacerbate the adverse effects of CsA inthe fashion that beclouds SRL, 649641P (NC1153) seems to exert selectiveactions on lymphoid elements.

From the foregoing investigations it can be concluded that 649641P(NC1153) blocks Jak3 activity, prolongs allograft survival alone and issynergistic with CsA. A preferred compound, 649641P (NC1153), showed invitro selective inhibition of Jak3- compared to Jak2-dependent T-cellproliferation and in vivo extended survivals of organ allografts withoutcausing any nephrotoxic side effects. Advantageously, 649641P (NC1153)displayed potent synergistic interaction with cyclosporine to prolongthe survival of the organ allograft without increasingcyclosporine-induced nephrotoxicity. Moreover, 649641P (NC1153) showsgreater specificity for blocking Jak3 but not Jak2 mediated cellactivities than the previously described compounds AG490 and PNU156804.Although it is not clear at the present time whether the above-describeddesirable pharmacologic properties associated with the administration of649641P (NC1153) are due entirely to the direct interaction of the649641P (NC1153) compound with Jak3, or, for example, if Jak3 inhibitionis mediated to any extent in vivo by a metabolite or derivative form of649641P (NC1153). In the latter event, it is envisioned that directadministration of any such active metabolite or derivative species maybe substituted therapeutically for 649641P (NC1153) if medicallyindicated. Likewise, a precursor compound that is acted on in vivo toyield one of the selective Jak3 inhibitor compounds described herein mayalso be administered therapeutically, if the particular needs of theindividual so indicate.

EXAMPLE 4 Therapeutic Applications

The 649641P (NC1153) compound is considered representative of themedical usefulness of the group of compounds described herein forimmunosuppressive therapies and for treating other pathologies oflymphoid, myeloid, or other cells containing or expressing Jak3. Thecompounds are considered especially useful in T-cell related diseases inhumans, and for use in veterinary practice, for any application where itis desirable to suppress a Jak3-dependent lymphoid or myeloid cellfunction without affecting the activity of other protein kinases, oraffecting such kinases to less, or therapeutically acceptable, extent.Treatment includes administering an amount of the compound effective tointerfere with the signal 3 pathway in a lymphocyte, or other cell oflymphoid or myeloid origin which expresses Jak3, and thereby inhibit itsfunction. For example, blocking cell division. Such administration mayutilize the acid form of the compound or a pharmaceutically acceptablesalt thereof, or it may be in the form of a biologically activemetabolite of the compound. Alternatively, a precursor compound may beadministered which is capable of being metabolized in the body of thesubject to one or more active forms of the compound, whereby aJak3-dependent lymphocyte function is disrupted, preferably blockingcell division. Administration may be continuous or periodic.

In some medical situations, the individual will be in need ofsuppression of an undesirable immune response, in which caseadministration of an effective amount of a pharmaceutical compositioncontaining 649641P (NC1153), or a precursor or active metabolite willmitigate or prevent the unwanted immune response. By co-administering atherapeutically effective amount of a different immunosuppressive agent,such as cyclosporin A or FK506, which do not act via Jak3 inhibition,even better results may be achieved with less toxicity to theindividual. Examples of such use include mitigating organ transplantrejection or allograft rejection in a mammalian transplant or allograftrecipient, or to induce transplantation tolerance. In other instances,the therapeutic goal may be to promote remission of an autoimmunedisease mediated by endogenous Jak3-dependent T-cells so that theautoimmune attack on the subject's native tissue is diminished orarrested. Still other avenues of use include administering apharmaceutical preparation of 649641P (NC1153) to mitigate airwayhypersensitivity in a mammalian subject by suppressing a T-cell mediatedhypersensitivity response. Similarly, allergy sufferers may be treatedto suppress a T-cell mediated allergic response and thereby diminish orarrest the allergic reaction. Administration of a pharmaceuticalcomposition containing 649641P (NC1153) is also expected to inhibitproliferation of Jak3-dependent leukemia or lymphoma. A notablepotential advantage of therapeutic treatment with 649641P (NC1153) isthat by selectively inhibiting Jak3 activity, which is limited to cellsof the lymphoid compartment (and Jak3 expressing myeloid cells), andhaving little or no effect on Jak2, and other protein kinase activitiesfound in many tissues throughout the body, far fewer side effects areexpected.

Pharmaceutical compositions. A pharmaceutical composition suitable fortherapeutic use contains the 649641P (NC1153) compound in its acid form,or a pharmaceutically acceptable salt or hydrate thereof, in combinationwith a suitable carrier. Pharmaceutically acceptable salts and hydratesrefer to those salts and hydrated forms of the compound which would beapparent to the pharmaceutical chemist, i.e., those which favorablyaffect the physical or pharmacokinetic properties of the compound, suchas solubility, palatability, absorption, distribution, metabolism andexcretion. Other factors, more practical in nature, which are alsoimportant in the selection of the form of the compound include the costof the raw materials, ease of crystallization, yield, stability,solubility, hygroscopicity and flowability of the resulting bulk drug.When the compound is negatively charged, it is balanced by a counterion,e.g., an alkali metal cation such as sodium or potassium. Other suitablecounterions include calcium, magnesium, zinc, ammonium, or alkylammoniumcations such as tetramethylammonium, tetrabutylammonium, choline,triethylhydroammonium, meglumine, triethanolhydroammonium, etc. Anappropriate number of counterions is associated with the molecule tomaintain overall charge neutrality. Likewise when the compound ispositively charged, e.g., protonated, an appropriate number ofnegatively charged counterions is present to maintain overall chargeneutrality.

Pharmaceutically acceptable salts also include acid addition salts.Thus, the compound can be used in the form of salts derived frominorganic or organic acids or bases. Examples include acetate, adipate,alginate, aspartate, benzoate, benzenesulfonate, bisulfate, butyrate,citrate, camphorate, camphorsulfonate, cyclopentanepropionate,digluconate, dodecylsulfate, ethanesulfonate, fumarate, glucoheptanoate,glycerophosphate, hemisulfate, heptanoate, hexanoate, hydrochloride,hydrobromide, hydroiodide, 2-hydroxyethanesulfonate, lactate, maleate,methanesulfonate, 2-naphthalenesulfonate, nicotinate, oxalate, pamoate,pectinate, persulfate, 3-phenylpropionate, picrate, pivalate,propionate, succinate, tartrate, thiocyanate, tosylate and undecanoate.Base salts include ammonium salts, alkali metal salts such as sodium andpotassium salts, alkaline earth metal salts such as calcium andmagnesium salts, salts with organic bases such as dicyclohexylaminesalts, N-methyl-D-glucamine, and salts with amino acids such asarginine, lysine, and so forth. Also, the basic nitrogen-containinggroups may be quaternized with such agents as lower alkyl halides, suchas methyl, ethyl, propyl, and butyl chloride, bromides and iodides;dialkyl sulfates like dimethyl, diethyl, dibutyl; and diamyl sulfates,long chain halides such as decyl, lauryl, myristyl and stearylchlorides, bromides and iodides, aralkyl halides like benzyl andphenethyl bromides and others. Other pharmaceutically acceptable saltsinclude the sulfate salt ethanolate and sulfate salts.

A Jak3 inhibitor compound described herein may be formulated in apharmaceutical composition by combining the compound with apharmaceutically acceptable carrier, as are known in the art. Thecompounds may be employed in powder or crystalline form, in solution orin suspension. They may be administered orally, parenterally(intravenously or intramuscularly), topically, transdermally or byinhalation. The carrier employed may be, as appropriate, a solid orliquid. Examples of solid carriers include lactose, terra alba, sucrose,talc, gelatin, agar, pectin, acacia, magnesium stearate, stearic acidand the like. Examples of liquid carriers include syrup, peanut oil,olive oil, water and the like. A carrier for oral use may include timedelay material well known in the art, such as glyceryl monostearate orglyceryl distearate alone or with a wax. Topical applications may beformulated in carriers such as hydrophobic or hydrophilic bases to formointments, creams, lotions, in aqueous, oleaginous or alcoholic liquidsto form paints or in dry diluents to form powders. Examples of oralsolid dosage forms include tablets, capsules, troches, lozenges and thelike. The size of the dosage form will vary widely, but preferably willbe from about 25 mg to about 500 mg. Examples of oral liquid dosageforms include solutions, suspensions, syrups, emulsions, soft gelatincapsules and the like. Examples of injectable dosage forms includesterile injectable liquids, e.g., solutions, emulsions and suspensions.Examples of injectable solids include powders which are reconstituted,dissolved or suspended in a liquid prior to injection. In injectablecompositions, the carrier is typically comprised of sterile water,saline or another injectable liquid, e.g., peanut oil for intramuscularinjections. Also, various pharmaceutically acceptable buffering agents,preservatives and the like may be included.

Dosage. Pharmaceutical compositions for implementing the therapeutic useof the Jak3-selective inhibitor compounds described herein includecompositions contain the active ingredients in an amount sufficient toachieve the intended purpose, i.e., the selective disruption orinhibition of Jak3 activity or the treatment or prevention of aJak3-related disorder. A therapeutically effective amount or dose can beestimated initially from cell proliferation assays, as presented herein.Then, the dosage can be formulated for use in animal models so as toachieve a circulating concentration range that includes the IC₅₀ asdetermined in cell culture (i.e., the concentration of the compoundwhich achieves a half-maximal inhibition of IL2 dependent proliferationand little or no inhibition of PRL dependent proliferation), as alsodemonstrated herein. Such information may then be used to moreaccurately determine a range of useful doses in humans and othermammals, in accordance with standard pharmacologic practices. The dosagemay vary depending upon the dosage form employed and the route ofadministration utilized. For instance, dosage amount and intervals maybe adjusted individually to provide plasma levels of the active specieswhich are sufficient to initiate and/or maintain the desired Jak3inhibitory effects. These plasma levels are customarily referred to asminimal effective concentrations (MECs). The MEC may vary from onecompound to another, but may be estimated from in vitro data, as notedabove. For example, the concentration necessary to achieve 50-90%inhibition of Jak3 autokinase activity in a population of T-cells may beascertained using the assays described herein. HPLC assays or bioassaysmay be employed to determine plasma concentrations. Dosage intervals canalso be determined using MEC value. Preferably the compound will beadministered using a regimen that maintains plasma levels above the MECfor the desired period of time. In treatments which include localadministration or selective uptake, the effective local concentration ofthe compound, or its active metabolite or derivative, may not beadequately reflected by plasma concentration. In this case, otherprocedures which are known in the art may be employed to determine anappropriate dosage amount and interval. An example of a suitable oraldosage range for an adult human is from about 0.1 to about 80 mg/kg perday, in single or divided doses. An example of a suitable parenteraldosage range is from about 0.1 to about 80 mg/kg per day, in single ordivided dosages, administered by intravenous or intramuscular injection.An example of a topical dosage range is from about 0.1 mg to about 150mg, applied externally from about one to four times a day. An example ofan inhalation dosage range is from about 0.01 mg/kg to about 1 mg/kg perday. The exact formulation, route of administration and dosage can bechosen by the individual physician in view of the patient's condition,the nature of the illness being treated, and other factors.

EXAMPLE 5 Additional Jak-3 Selective Inhibitor Compounds

In the preceding Examples it was demonstrated that 649641P (NC1153)selectively or specifically inhibits the proliferation and function ofJak3-containing T-cells, prolongs allograft survival, and demonstrateslow toxicity. In view of these evaluations, it is clear that 649641P(NC1153) has probable therapeutic value for treating individuals havingimmune-related disorders. This compound is also valuable as a reagentfor use as a standard for comparison in evaluating other candidate drugcompounds with respect to selectivity for inhibition or disruption ofJak3 in vitro assays and in vivo studies.

As noted above, in the course of the present investigations the NCI DrugDiscovery Database was scanned for additional candidate compounds thatmight serve as selective inhibitors of Janus kinase 3 (Jak3). Compoundsthat displayed a similar correlation coefficient to the “seed” compoundAG490, a tyrphostin with Jak3 inhibitory potential, were assessed.

COMPARE Algorithm. The NCI drug database is comprised of hundreds ofthousands of compounds that have been gathered from various sectors ofthe world. These include donations of drugs that range from largepharmaceutical companies to small privately owned laboratories. In manyinstances these compounds were added to test and promote the library.However, many of these compounds have been discontinued by themanufacturer due to ineffectiveness for its originally proposed functionand in some instances the submitting company is no longer in operation.Regardless of the status of the drug, its structure and resultingactivity has been added to the library database which is updated weekly.

The database was generated by testing a dose response for a particulardrug against 60 distinct human cell lines (e.g., epithelial, lung,colon, monocyte/macrophage, T-B cells, breast-prostrate, etc). Threeparameters are measured include inhibition of cell growth (IC₅₀),cytotoxic (LC₅₀), and cytostatic effects (TGI). Together, they comprisea mean graph “signature” for each compound. Drugs that display apositive value (project to the right) are reflective cellularsensitivities that exceed the mean. Negative values (project to theleft) indicate that cell lines are less sensitive to the test agent thanthe average. COMPARE is an algorithm that rank-orders each compoundbased on its activity in vitro to a predetermined “seed”, as in thepresent case AG-490. Mean graphs are converted for each drug to a scalarindex rating using. Pearson's correlation coefficient (PCC). Ultimately,drugs with the most similar effects will show high-ranking correlation(approaching 1) and likely to possess mechanisms of action similar tothat of the seed compound.

COMPARE has been successful in identifying compounds with similarmechanisms of action. This is a hypothetical model based on the premisethat similar drugs that, for example, block cell growth will target thesame critical target pathway in a similar cell type. Cells that relyheavily on a particular pathway will be sensitive to inhibition of thatpathway (such as cells that express JAK3/Stat5), whereas cells that failto express such molecules or are less dependent on this pathway, thesame drugs will have little or no effect. This allows COMPARE to grouptogether drugs with similar mechanisms of action across a panel ofcells.

A number of different studies completed to date have shown that thisapproach has been successful for identifying new agents whichselectively affect the same molecular target, thus yielding adistinctive mean graph pattern. The COMPARE algorithm can identifysimilar mean patterns for a compound of distinct structure, but with thesame mechanism of action compared to the seed. Laboratory studies needto confirm the match within a particular read-out (JAK3 Stat5phosphorylation). COMPARE does not necessarily rely on chemicalstructure as it does similar mechanisms of drug action. This allows foridentification of structurally novel classes of compounds that werenever before recognized as a particular inhibitor for a given target.The effectiveness of this approach has been borne out by identifyinginhibitors of p53, Raf, topoisomerase, and tubulin binding proteins.Once a structural class of known mechanisms of action is discovered thenadditional screening of available analogues and synthesis of new onescan be used to define and optimize a drug of interest.

Among the compounds identified in the above-mentioned NCI drug databasescreening were 649641P (NC1153) and several congeners or structuralanalogs of 649641P. The effect of the compounds 637712, 640674, 643423,655906, 673137, 683332 and 693812 (denoted by their NCI databasenumbers) on T-cell proliferation was assessed and compared to theeffects of AG490, PNU156804 and 649641P (NC1153). The results of thosecomparative assays are shown in bar graph form in FIG. 7A. It can beseen that proliferation of PHA-activated human T cells is blocked bythese NCI agents following stimulation with IL-2. The structural formulaof NC1153 is shown in the inset. NC1153 failed to affect IL2 receptorexpression.

Also shown (FIG. 7B) is a graph showing the FACS analysis ofPHA-activated T-cell blasts that were treated without (heavy line) orwith 50 μM NC1153 (light line) overnight and stained for IL2R-α, -β, and-γ chains. The dashed lines indicate cells pretreated with NC1153. Theseresults show that the presence of the IL-2 receptors is unaffected bythe NC1153. These findings demonstrate that the loss of IL2 signals isnot due to changes in receptor expression, thus occurring distal to theIL2 receptor, hence Jak3. As shown in FIG. 7C, the NC1153 compound doesnot block cell growth of non-Jak3 expressing cells. Jurkat cells (blackdiamonds) which fail to express Jak3 do not show significant change incell growth following treatment with NC1153 in contrast to Jak3containing PHA activated T-cells (open boxes). Data are normalized aspercent of vehicle control. NC1153 inhibits growth of cells by cytokinesthat utilize Jak3 and the common gamma chain (FIG. 7D). As also shown inFIG. 1A, T-cell proliferation of 649641P (NC1153) treated T-cellsinhibits IL2, IL4 or IL7 driven growth normalized to untreated controlsin a dose dependent manner. Thus, the inhibitory effects of NC1153 arenot limited to cells stimulated only by IL-2. Instead, the entire familyof cytokines which use Jak3 are blocked by NC1153.

Referring now to FIG. 8, direct evidence is provided that 6496421P(NC1153) inhibits Jak3 signaling pathways. Jak3 autokinase activity isdirectly blocked by NC1153 based on in vitro analysis. The bandsidentified as “PY-Jak3” reveal only the active Jak3 at the indicateddosages of NC1153, with or without IL-2 and ATP. The bands identified as“Jak3” reveal the presence of total (active plus inactive) Jak3 protein.To show that inhibiting Jak3 blocks downstream pathways, immunopurifiedJak3 was assayed for Jak3 autokinase activity and tested byphosphotyrosine Western blot in the absence or presence of 100 μM ATPand/or drug and compared to controls, as shown in FIGS. 2A-C. It wasalso observed that 649641 (NC1153) showed an IC₅₀ of approximately 2.5μM that parallels the proliferation data, as shown in FIGS. 7A and 7D.

FIGS. 9A-C show that NC1153 does not inhibit non-Jak3 signalingpathways. In FIG. 9A, it can be seen that NC1153 inhibits Jak3 driventranscription factor-Stat5a/b in PHA activated T-cells treated withincreasing concentrations of NC1153 in a dose dependent manner asmeasured via EMSA analysis (upper panel). The lane identified as “coldcompete” contains unlabeled probe. However, non-Jak3 mediated NfκBactivation (lower panel) by TNF-α was not affected within the sametreatment set. The results shown in FIG. 9B establish that NC1153 failsto inhibit the closely related Jak2/Stat5a signaling pathway. Rat Nb2cells were treated with increasing concentration of NC1153 and thenstimulated with prolactin. Phosphotyrosine Western blots detectactivation but no inhibition by NC1153. In Stat5a/b activation Jak3mediated Jak3 autokinase activity is directly blocked by NC1153 based onin vitro analysis. NC1153 fails to affect activity of multiple kinases.At least 50 fold more inhibition of Jak3 than Jak2 in kinase assays isshown in FIG. 9B and FIG. 8. As shown in FIG. 9C, NC1153 was tested at10 or 50 μM to block growth factor tyrosine kinases (FGFR3 and PDGFRα),Src family tyrosine kinases (Src, Fyn, Lck, Yes, Zap70) or serinethreonine kinases (PKC and PKA) phosphorylation of a substrate. Activityof the control is plotted as a dashed line.

FIGS. 10A-D summarize the in vivo effects of 649641P (NC1153) onallograft survival (presented in Table 1.) ACI rat recipients of Lewis(LEW) kidney allografts were treated for 7 days with NC1153 delivered bydaily i.v. injections or by oral gavage. Allograft survival time (days)at varying drug dosage is shown in FIG. 10A, and individual survivalsare shown in Table 1. ACI rat recipients of LEW kidney allografts weretreated for 14 days with NC1153 delivered by daily oral gavage. Thegraft survival rate (days) is shown at varying dosages of NC1153) inFIG. 10B. ACI rat recipients of LEW kidney allografts were treated for 7days and thereafter 3×/week up to 90 days with 160 mg/kg NC1153delivered by daily oral gavage. As shown in FIG. 10C, 75% of the treatedrecipients survived to beyond treatment of 90 days with survival timesexceeding 200 days. Induction of transplantation tolerance was confirmedby acceptance of LEW donor-(>100 days; n=3) but not third-party BUF(7.0±1.0 days; n=3) heart allografts by long-term surviving recipients.The mechanism of tolerance was examined when irradiated (400 rads) ACIrecipients of LEW heart allografts were adoptively transferred with30×10⁶ purified T cells from tolerant recipients. Recipients transferredwith tolerant T cells displayed significantly delayed rejection of LEWheart allografts (40.0±15.0 days; n=6 vs 15±1.0 days; n=5 in irradiatedcontrols) with 2 hearts beating well for >100 days, but rejectedthird-party heart allografts (12±1.0 days; n=2). These results suggestthat transplantation tolerance was mediated at least in part by T cellregulatory cells (not shown). FIG. 10D shows a summary of the resultspresented above in Table 2 regarding ACI rat recipients of LEW kidneyallografts treated for 7 days with NC1153 alone, with CsA alone, andwith the combined drugs, delivered by daily oral gavage. The MST of eachtreatment group at each dosage level is shown and below chart displaythe low CI values indicating that the NC1153-CsA combination issynergistic.

As shown in FIGS. 11A-F, 649641P (NC1153) is not nephrotoxic and doesnot affect lipid metabolism. Rats fed low-salt diet (7 days prior andduring 14 day therapy) were treated by oral gavage with 160 mg/kg NC1153alone or in combination with 5 mg/kg CsA; some animals were treated byoral gavage with 0.8 mg/kg rapamycin (RAPA) alone or in combination with5 mg/kg CsA. Kidney function was evaluated by serum creatinine levelsand serum creatinine clearance, and the results are shown in FIGS. 11Aand 11B, respectively. Lipid metabolism was evaluated by measuring ofserum cholesterol (FIG. 11C), triglycerides (FIG. 11D), LDL-cholesterol(FIG. 11E), and HDL-cholesterol (FIG. 11F). The effect of NC1153 aloneor in combination with CsA on kidney structure was determined. Rats onlow-salt diet for 7 days were treated for 14 days with: 10 mg/kg NC1153delivered i.v.; 0.16 mg/kg RAPA delivered i.v.; 10 mg/kg CsA deliveredby oral gavage; combination of 10 mg/kg CsA p.o. with 0.16 mg/kg RAPAi.v.; or combination of 10 mg/kg CsA p.o. with 10 mg/kg 641P i.v. On day14 rats were sacrificed and histology performed on kidneys using H&Estaining. Similar results were observed in 5 rats per group. As shown inFIGS. 6A-E, neither 649641P (NC1153) alone nor RAPA alone showed anysignificant changes in the kidneys. In contrast, CsA alone caused damagein 30% of tubuli with vacuolization and atrophy. The CsA/RAPA groupshowed massive vacuolization in 90% of tubuli with atrophy and pyknoticnuclei. In contradistinction to the CsA/RAPA group, kidneys from ratstreated with the CsA/NC1153 combination showed changes similar to thoseobserved in the CsA alone group.

The meso stereoisomer of 649641P (NC1153), designated WP938 (shown inFIG. 18B) was synthesized using a procedure which included the followingsteps: to 0.1 mmol of cycloalkanoneone and 0.21M ofN,N,N′,N′-tetramethyldiaminomethane dissolved in 400 mL of acetonitrilewas added dropwise in 40 minutes 16.5 g (0.21 mol) of acetyl chloride.After reaction was completed the crude product precipitated, filtered,washed with ether and dried. Subsequent crystallizations led to pureproduct.

The resulting WP938 compound was tested for its effect on allograftsurvival and for toxicities, when administered alone or in combinationwith CsA. The results are shown in FIGS. 12A,B-13A-F. It was found thatWP938 alone delivered by oral gavage for 7 days at doses 20-160 mg/kgextended in dose-dependent fashion the survivals of ACI recipients ofLEW kidney allografts (FIG. 12A). Combination of 1.25 mg/kg CsA and 160mg/kg WP938 delivered p.o. for 7 days produced synergistic interactionon kidney allograft survival, as documented by the CI value of 0.44.(FIG. 12B) As shown in FIGS. 13A-F, a 14-day oral therapy with 160 mg/kgWP938 produced no changes in chemistries and blood elements countsdocumenting lack of toxicities. Serum creatinine and creatinineclearance showed lack of nephrotoxcicity by WP938 and no effect onCsA-induced nephrotoxicity. (FIGS. 13A,B). FIG. 13C indicatescholesterol levels. FIG. 13D indicates triglyceride. FIG. 13E indicatesHDL levels. FIG. 13F indicates LDL levels.

FIG. 14B through FIG. 39B show the chemical formulas of various Mannichbase compounds and others (shown as salts) that were screened forability to inhibit proliferation in prolactin or IL2 stimulated T-cells.FIGS. 14A through 39A show the results of those assays over theindicated concentration range. The screening assays were carried outsubstantially as described in the general methods, above. Compoundshaving the apparent characteristic of not blocking Jak2 and Stat5a/bactivation by prolactin (PRL) (dark squares) at concentrationssufficient to inhibit Jak3 and Stat5a/b activated by IL2 (light squares)were identified for further evaluation. The preferred 649641P (NC1153)compound and its selective inhibitory activity are shown in Example 1and FIGS. 1A,B. Additional candidate drugs, the compounds shown in FIGS.14B-17B and 19B-39B, which demonstrated at least some amount ofselective inhibitory activity with respect to PRL or IL2 stimulatedT-cells at specified concentrations, are the subject of ongoinginvestigations in the same manner as described in the foregoing examplesemploying the representative compound 649641P (NC1153). Whereapplicable, these compounds may have asymmetric centers and occur asracemates, racemic mixtures and as individual diastereomers, orenantiomers with all isomeric forms being included, for the purposesdisclosed herein. For example, with respect to Formula (I), theconfiguration at C-2 and C-12 may be (R) or (S). These compounds,including all stereoisomers, which are determined to be sufficientlynon-toxic and which are able to significantly prolong allograft survivalas demonstrated herein for 649641P (NC1153) will also have probabletherapeutic value in humans and for veterinary use in immunosuppressivetherapies. They are also expected to be of therapeutic value fortreating other pathologies related to Jak3 expressing cells of lymphoidor myeloid origin. As was demonstrated for 649641P (NC1153) and WP938,it is believed that some of these candidate drug compounds will alsodemonstrate synergistic activity when administered with CsA or otherimmunosuppressive agents that exert their immunosuppressive effects bypathways other than Jak3-related pathways.

Definitions

In addition to having their customary and usual meaning, the followingdefinitions apply where the context permits in the specification andclaims:

“Selective inhibition” refers to a chemical compound that preferentiallyblocks the function of one protein and to a lesser degree one or moreknown proteins.

“Specific inhibition” refers to a chemical compound that solely blocksthe function of a given protein without affecting other proteins.

“Immunosuppressive potential” refers to a chemical compound that shouldreduce or ablate an immune response (e.g. a drug that blocks rejectionof a transplanted organ allograft).

“Pharmaceutical composition” refers to a mixture of one or morechemicals, or pharmaceutically acceptable salts thereof, with a suitablecarrier, for administration to a mammal as a medicine.

“Lymphoid cells” refer to cells of immune origin, or, more specifically,cells derived from stem cells of the lymphoid lineage, including largeand small lymphocytes and plasma cells. Examples of lymphoid cells areT-cells, B-cells and natural killer (NK) cells.

“Myeloid cells” refers to cells of myeloid origin, i.e., derived fromstem cells of myeloid lineage, including monocytes, macrophages anddendritic cells.

“Drug” refers to a chemical compound suitable for medical use.

“Congener” or cogener refers to a chemical compound closely related toanother in composition (e.g., a structural analog) and exerting similaror antagonistic effects.

“Therapeutically effective amount” refers to that amount of the compoundbeing administered that will relieve at least to some extent one or moreof the symptoms of the disorder being treated. For example, an amount ofthe compound effective to prevent, alleviate or ameliorate symptoms ofdisease or prolong the survival of the subject being treated.

With respect to a disease or disorder, the term “treatment” refers topreventing, deterring the occurrence of the disease or disorder,arresting, regressing, or providing relief from symptoms or side effectsof the disease or disorder and/or prolonging the survival of the subjectbeing treated.

REFERENCES

-   1. Kane L P, Lin J, Weiss A. Signal transduction by the TCR for    antigen. Curr Opin Immunol. (2000) 12L2420249.-   2. Denton, M D, Magee C C, Sayegh M H. Immunosuppressive strategies    in transplantation. Lancet (1999) 353:1083-1091.-   3. Mihatsch M J, Kyo M, Morozumi K, et al. The side effects of    Cyclosporin-A and Tacrolimus. (1998) Clin. Nephrol 49:356-363.-   4. Kahan B D, Camardo J S. Rapamycin: clinical results and future    opportunities. Transplantation (2001) 72:1181-1193.-   5. Kirken R A, Stepkowski S M. New directions in T-cell signal    transduction and transplantation tolerance. Transplant (2002)    7:18-25.-   6. Weiss A, Littman D R. Signal transduction by lymphocyte antigen    receptors. Cell. (1994) 76:263-274.-   7. Irving B A, Chan A C, Weiss A. Functional characterization of a    signal transducing motif present in the T cell antigen receptor zeta    chain. J Exp Med. (1993) 177:1093-1103.-   8. Chan A C, Kadlecek T A, Elder M E, et al. ZAP-70 deficiency in an    autosomal recessive form of severe combined immunodeficiency.    Science. (1994) 264:1599-1601.-   9. Appleby M W, Gross J A, Cooke M P, Levin S D, Qian X, Perlmutter    R M. Defective T cell receptor signaling in mice lacking the thymic    isoform of p59fyn. Cell. (1992) 70:751-763.-   10. Kuo C T, Leiden J M. Transcriptional regulation of T lymphocyte    development and function. Annu Rev Immunol. (1999) 17:149-187.-   11. Leonard W J, O'Shea J J. JAKs and STATs: biological    implications. Annu Rev Immunol. (1998); 16:293-322.-   12. Kondo M, Takeshita T, Ishii N, et al. Sharing of the    interleukin-2 (IL-2) receptor gamma chain between receptors for IL-2    and IL-4. Science. (1993) 262:1874-1877.-   13. Noguchi M, Nakamura Y, Russell S M, et al. Interleukin-2    receptor gamma chain: a functional component of the interleukin-7    receptor. Science. (1993); 262:1877-1880.-   14. Russell S M, Keegan A D, Harada N, et al. Interleukin-2 receptor    gamma chain: a functional component of the interleulin-4 receptor.    Science. (1993) 262:1880-1883.-   15. Russell S M, Johnston J A, Noguchi M, et al. Interaction of    IL-2R beta and gamma c chains with Jak1 and Jak3: implications for    XSCID and XCID. Science. (1994) 266:1042-1045.-   16. Kirken R A, Rui H, Malabarba M G, et al. Activation of JAK3, but    not JAK1, is critical for IL-2-induced proliferation and STAT5    recruitment by a COOH-terminal region of the IL-2 receptor    beta-chain. Cytokine. (1995) 7:689-700.-   17. Malabarba M G, Rui H, Deutsch H H, et al. Interleukin-13 is a    potent activator of JAK3 and STAT6 in cells expressing interleukin-2    receptor-gamma and interleukin-4 receptor-alpha. Biochem J. (1996)    319:865-872.-   18. Szabo S J, Glimcher L H, Ho I C. Genes that regulate    interleukin-4 expression in T cells. Curr Opin Immunol. (1997)    9:776-781.-   19. Kirken R A, Rui H, Malabarba M G et al. J Biol Chem (1994)    269:19136.-   20. Johnston J A, Kawamura M, Kirken R A, et al. Nature (1994)    370:151.-   21. Kirken R A. Transplantation Proceedings (2001) 33:3268-3270.-   22. Thomis T C, Berg L J. Curr Opin Immunol (1997) 9:541.-   23. Kirken R A, Erwin R A, Taub D, et al. Tyrphostin AG490 inhibits    cytokine-mediated Jak3/Stat5a/b signal transduction and cellular    proliferation of antigen-activated human T-cells. J Leukoc    Biol (1999) 65:891-899.-   24. Behbod F, Erwin-Cohen R A, Wang M -E, et al. Concomitant    inhibition of Janus kinase 3 and calcineurin-dependent signaling    pathways synergistically prolongs the survival of rat heart    allografts. J Immunol (2001) 166:3724-3732.-   25. Stepkowski S M, Erwin-Cohen R A, Behbod F et al. Selective    inhibitor of Janus tyrosine kinase 3, PNU156804, prolongs allograft    survival and acts synergistically with cyclosporine but additively    with rapamycin. Blood (2002) 99:680-689.-   26. Yamashita H, Xu J, Erwin R A, Farrar W L, Kirken R A, Rui H.    Differential control of the phosphorylation state of    proline-juxtaposed serine residues Ser725 of Stat5a and Ser730 of    Stat5b in prolactin-sensitive cells. J Biol. Chem. (1998)    273:30218-30224.-   27. Kirken R A, Rui H, Malabarba M G, et al. Activation of JAK3, but    not JAK1, is critical for IL-2-induced proliferation and STAT5    recruitment by a COOH-terminal region of the IL-2 receptor    beta-chain. Cytokine. (1995) 7:689-700.-   28. Ono K, Lindsey E S. Improved technique of heart transplantation    in rats. J Thorac Cardiovasc Surg. (1969) 57:225-229.-   29. Chou T -C. The median effect principle and the combination index    for quantitation of synergism and antagonism. In: Chou T -C, Rideout    D, Eds. Synergism and antagonism in chemotherapy. San Diego, Calif.:    Academic Press, Inc, 1991:61-102.-   30. Chou J, Chou T -C. Dose-effect analysis with microcomputers:    quantitation of ED50, LD50, synergism, antagonism, low-dose risk,    receptor-ligand binding and enzyme kinetics. Biosoft, Cambridge, UK.    1987.-   31. Schrader B, Steinhoff G. Models of inflammatory cascade    reactions by adhesion molecules. In: Steinhoff G, Ed. Cell adhesion    molecules in human organ transplants. Austin: R G Lands Company,    1993:71-86.-   32. Winters G L, Marboe C C, Billingham M E. The international    society for heart and lung transplantation grading system for heart    transplant biopsy specimens: Clarification and commentary. J Heart    Lung Transplant. 1998; 17:754-760.-   33. Thomis D C, Berg L J. Peripheral expression of Jak3 is required    to maintain T lymphocyte function. J Exp Med (1997) 185: 197-206.-   34. Dimmock J R, Kumar P. Anticancer and Cytotoxic Properties of    Mannich Bases. Current Medicinal Chemistry (1997) 4:1-22.-   35. Dimmock J R, Chamankhah M, Seniuk A et al. Synthesis and    Cytotoxic Evaluation of Some Mannich Bases of Alicyclic Ketones.    Pharmazie (1995) 50:668-671.

While the preferred embodiments of the invention have been shown anddescribed, modifications thereof can be made by one skilled in the artwithout departing from the spirit and teachings of the invention. Theembodiments described herein are exemplary and representative, and arenot intended to be limiting. Many variations and modifications of theinvention disclosed herein are possible and are within the scope of theinvention. Although the foregoing discussion focuses on T-cell derivedgraft vs. host disease, it will be readily appreciated that the methods,compounds and compositions described herein are also likely to haveapplication in other T-cell dependent diseases or disorders. Forexample, they may be useful for treating autoimmune diseases such aslupus, arthritis and multiple sclerosis, or for treating allergy,asthma, psoriasis, ulcerative colitis, lymphomas, and leukemias.Selective Jak3 targeted inhibition is also expected to also haveapplication in many other immune-derived pathologies, or in Jak3expressing myeloid cell derived pathologies, including hyperactiveimmune system responsive conditions derived from hyperactive or unwanteddendritic cell, B-cell, monocyte, macrophage or natural killer cellderived conditions. Accordingly, the scope of protection is not limitedby the description set out above, but is only limited by the claimswhich follow, that scope including all equivalents of the subject matterof the claims. All patents, patent applications and publications citedherein are hereby incorporated herein by reference to the extent thatthey provide materials, methods and explanatory details supplementary tothose set forth herein. The discussion of certain references in theDescription of Related Art, above, is not an admission that they areprior art to the present invention.

1. An in vitro method of suppressing Janus tyrosine kinase 3(Jak3)-dependent proliferation of a cell expressing Janus tyrosinekinase 3, comprising: selectively targeting Jak3 activity in the cellfor inhibition by contacting the cell with at least one compound of theformula (I)

wherein R₁ is H, ═CH₂, CH₂N(CH₃)₂, CH₂SC(O)CH₃, CH₂SC₆H₅,CH₂SCH₂-(4-C₆H₄OCH₃), CH₂SC(O)C₆H₅ or CH₂N(CH₂CH₃)₂; R² is O; R³ isCH₂N(CH₃)₂, CH₂N(CH₂CH₃)₂ or CH₂—(N-morphyl); or a salt thereof, at aconcentration effective to selectively inhibit Janus tyrosine kinase 3activity, whereby Jak3-dependent proliferation of the cell issuppressed.
 2. The method of claim 1 wherein R¹ is CH₂N(CH₃)₂ and R³ isCH₂N(CH₃)₂.
 3. The method of claim 2 wherein said compound is the mesostereoisomer.
 4. The method of claim 1 wherein the cell is of lymphoidor myeloid origin.
 5. The method of claim 1 wherein selectivelyinhibiting Jak3 activity interferes with the signal 3 pathway, such thatcell division is blocked.
 6. The method of claim 1 wherein, at saidconcentration effective to selectively inhibit said Janus tyrosinekinase 3, said at least one compound is non-inhibitory or is lessinhibitory of protein tyrosine kinase activity other than Janus tyrosinekinase 3 activity.
 7. The method of claim 1 wherein said cell is aT-cell expressing Jak3 and Janus tyrosine kinase 2 (Jak2), and themethod comprises inhibiting Jak3 activity at least 3 fold more thaninhibiting Jak2 activity in said T-cells.
 8. The method of claim 1comprising choosing at least one said compound which is less capable ofinhibiting Jak2 and Stat5a/b activation by prolactin (PRL) at aconcentration sufficient to inhibit Jak3 and Stat5a/b activated by IL2.9. The method of claim 4 wherein said cell is selected from the groupconsisting of T-cells, B-cells, natural killer (NK) cells and monocytes.10. The method of claim 1 wherein R¹ is H.
 11. The method of claim 1wherein R¹ is ═CH₂.
 12. The method of claim 1 wherein R¹ is CH₂N(CH₃)₂.13. The method of claim 1 wherein R¹ is CH₂SC(O)CH₃.
 14. The method ofclaim 1 wherein R¹ is CH₂SC₆H₅.
 15. The method of claim 1 wherein R¹ isCH₂SCH₂-(4-C₆H₄OCH₃).
 16. The method of claim 1 wherein R¹ isCH₂SC(O)C₆H₅.
 17. The method of claim 1 wherein R¹ is CH₂N(CH₂CH₃)₂. 18.The method of claim 1 wherein R³ is CH₂N(CH₃)₂.
 19. The method of claim1 wherein R³ is CH₂N(CH₂CH₃)₂.
 20. The method of claim 1 wherein R³ isCH₂-(N-morphyl).
 21. An in vitro method of suppressing undesired Janustyrosine kinase 3-dependent proliferation of a cell expressing Janustyrosine kinase 3, comprising: selectively targeting Janus tyrosinekinase 3 activity in the cell for inhibition by contacting the cell witha compound of the formula

or a salt thereof, at a concentration effective to selectively inhibitthe activity of said Janus tyrosine kinase 3 and thereby suppressingundesired Janus tyrosine kinase 3-dependent proliferation of said cell.22. An in vivo method of suppressing an undesired Jak3-dependentfunction of a cell expressing Janus tyrosine kinase 3 (Jak3) in amammalian allograft recipient, comprising: administering to saidallograft recipient a therapeutically effective amount of apharmaceutical composition containing at least one compound of theformula (I)

wherein R¹ is H, ═CH₂, CH₂N(CH₃)₂, CH₂SC(O)CH₃, CH₂SC₆H₅,CH₂SCH₂-(4-C₆H₄OCH₃), CH₂SC(O)C₆H₅ or CH₂N(CH₂CH₃)₂; R² is O; R³ isCH₂N(CH₃)₂, CH₂N(CH₂CH₃)₂ or CH₂-(N-morphyl), or pharmaceuticallyacceptable salt thereof, in a pharmaceutically acceptable carrier, tosuppress proliferation of a cell expressing Jak3 in said recipient totreat allograft rejection in said recipient.
 23. The method of claim 22wherein said cell is a T-cell and said amount of said pharmaceuticalcomposition is effective to block cell division in said T-cell.
 24. Themethod of claim 23 wherein said undesired function comprises a t-cellmediated immune response, and wherein blocking cell division in aplurality of said t-cells provides T-cell mediated immunosuppression insaid allograft recipient.
 25. The method of claim 22 comprisingcontinuously administering said pharmaceutical composition to theallograft recipient.
 26. The method of claim 22 comprising periodicallyadministering said pharmaceutical composition to the allograftrecipient.
 27. The method of claim 22 wherein suppression of saidundesired Jak3-dependent cell function comprises interfering with thesignal 3 pathway in the cell.
 28. The method of claim 22 wherein onesaid compound is represented by the formula

or a salt thereof.
 29. The method of claim 22, wherein saidadministering of said composition enhances allograft survival in saidmammalian allograft recipient.
 30. The method of claim 22 wherein R¹ isH.
 31. The method of claim 22 wherein R¹ is ═CH₂.
 32. The method ofclaim 22 wherein R¹ is CH₂N(CH₃)₂.
 33. The method of claim 22 wherein R¹is CH₂SC(O)CH₃.
 34. The method of claim 22 wherein R¹ is CH₂SC₆H₅. 35.The method of claim 22 wherein R¹ is CH₂SCH₂-(4-C₆H₄OCH₃).
 36. Themethod of claim 22 wherein R¹ is CH₂SC(O)C₆H₅.
 37. The method of claim22 wherein R¹ is CH₂N(CH₂CH₃)₂.
 38. The method of claim 22 wherein R³ isCH₂N(CH₃)₂.
 39. The method of claim 22 wherein R³ is CH₂N(CH₂CH₃)₂. 40.The method of claim 22 wherein R³ is CH₂-(N-morphyl).